Uncle Grandpa loved Pizza Steve in every other way as more than just a friend, even sexually. In fact, he had wanted to lose his virginity to the pizza slice ever since they had acquainted themselves. Pizza Steve himself had always been in love with Giant Realistic Flying Tiger, mainly because GRFT had a reputation for being very sultry and aggressive whenever she went into heat. (Pizza Steve had a thing for raging, seductive women.) Uncle Grandpa was completely oblivious to the passion Pizza Steve had for GRFT, however, and so he was convinced that his pizza slice friend/crush was in need of some assurance.
One day, Uncle Grandpa couldn't resist his urges any longer and confronted Pizza Steve after a long day of assisting people with their dilemmas.
"Pizza Steve?" Uncle Grandpa spoke out to his friend.
"Yeah?" Pizza Steve replied. "What's up, man?"
"I just wanted to ask you something."
"Uh-huh. Make this quick because I'm fixing to do something soon and I do mean, soon."
"H-how would you react if..."
"...I told you that I loved you and that I wanted you to take my virginity?"
A long pause ensued. Pizza Steve couldn't help but be shocked at what he had just heard. Uncle Grandpa eagerly waited for a response from the object of his affections while he fidgeted with his red-haired mustache.
Finally, Pizza Steve spoke, "I think I'd just be confused."
"Confused?" Uncle Grandpa asked, baffled himself. "By what? Me loving you or me wanting you to take my virginity?"
"Eh, both." Pizza Steve answered rather timidly. "Besides, I'm in love with Giant Realistic Flying Tiger."
Uncle Grandpa's lower lip began to quiver and pout, and he looked as though he were going to burst into tears any moment now. Fortunately, he managed to remain composed, at least long enough to rush over to Pizza Steve and kiss his cheesy, saucy lips.
"Dude, why'd you do that?" Pizza Steve asked, a bit miffed by Uncle Grandpa's romantic oral gesture.
The old human male managed to keep himself from bursting into tears over his pizza slice crush's insensitivity and replied, "Listen, Pizza Steve. I love you more than life itself. You are one of my very best friends and I'll never be able to forget that. It's not just sex that makes a relationship work; that's only the physical aspect and the physical extension of it. It's the unconditional love you feel for someone that makes it all worth it when you've stopped breathing and left the Earth. It's that love that'll drive someone like me to kill themselves over someone like you if it means saving their lives. Don't believe me? I'll prove it right now..."
There was a brief pause after that. Then, without uttering a single word, Uncle Grandpa proceeded to pull out his left eye with his left pinkie and his left thumb. Blood immediately began to flow profusely where his left eye once was, triggering a long horrifying scream from Pizza Steve. Upon hearing the scream, Gus the swamp monster and Giant Realistic Flying Tiger burst into the room.
"Pizza Steve, what's wrong?" Gus asked out of concern before catching a glimpse at Uncle Grandpa's left eye socket. "Oh my God, Uncle Grandpa! Your left eye is gone!"
"Yeah!" Pizza Steve butted in, still frightened by what he had just witnessed. "He pulled it out himself! Can you even believe how much blood is coming out of there, man?!"
Gus shook his head in disbelief. Then he noticed that Pizza Steve's vagina was now wet, apparently from watching Uncle Grandpa pull out his left eye.
"Pizza Steve?" Gus started to question. "Is there something you've been hiding from us?"
"What?" Pizza Steve replied, initially confused. Then he looked down at his vagina. "Oh, right. I'm not sure how to tell you this, but... I'm kinda one of each sex."
"Really?" Uncle Grandpa asked in shock. "That's actually kinda awesome, Pizza Steve! Also, I hope you believe me now when I say that I love you."
Gus and GRFT found themselves gaping at Uncle Grandpa's statement. Shortly afterward, GRFT felt a surge of lust and aggression run through her body and she let out a great, powerful roar which caught Gus so off-guard he lost his balance and fell over.
"Hey now..." Pizza Steve said in a sultry voice. "Now that's my girl..."
"Uh oh." Gus said aloud. "I think it's that time again."
"Oh yeah!" Pizza Steve exclaimed with confidence.
Pizza Steve ran underneath GRFT and shoved himself up her vagina. Shortly afterward, Uncle Grandpa proceeded to run behind GRFT and thrust his meat tube into Pizza Steve's vagina. Gus could only watch in amazement as the human male, pizza slice, and the tigress all engaged in interspecies coitus. All three of them screamed and moaned and growled as loudly as they could while they fucked in sync. (Gus even had to time their orgasms at one point to see if they were happening simultaneously.) Finally, the ordeal ended when GRFT and Pizza Steve were oozing with milky-white seminal fluid.
Three months later...
Giant Realistic Flying Tiger gave birth to a litter of five cubs, three girls and two boys, who happened to be the world's first hybrids between a tiger and a pizza slice. Each of the cubs looked just like their mother, but that's where the similarity ended. All of the cubs had cheese where their fur should've been and they were covered with pepperoni slices. Plus, they spoke fluent English and were somewhat anthropomorphic.
Their father himself was carrying what would be the world's first hybrid between a human being and a pizza slice in his womb. He was just going to exit his first trimester now and Uncle Grandpa couldn't be happier.
Uncle Grandpa, now having realized that Pizza Steve reciprocated feelings for the man who had fathered his child, decided that the love triangle could easily be fixed if all three of them got married. And so, that's how the first polygamous marriage between a human being, a pizza slice, and a tigress came to be when Uncle Grandpa married Pizza Steve who married Giant Realistic Flying Tiger.