why do guys only like girl with big butt??

It's our inner biological tendencies. A wider pelvis means a bigger pelvic gap which sort of implies more support during childbirth at least to our caveman sensibilities. And its soft as fuck and you can peacefully rest your face on it.

because we like big butts and we cannot lie *cue music*

Same reason women feel attracted to 6 packs? It's just how we are biologically programmed. Everybody appreciates a nice physique. Obviously people will have different interests, some may prefer a slender look, others appreciate some thickness. There's someone out there for everyone.

Nice asses are more of a bonus and not a necessity as it is with certain ethnic groups. The only thing that matters is how much they dig dark memes, Balkan war music, and world politics. Also, real sly there, Fox :p...

You haven't watched prison school have you Simply put boobs are imitation butts.

Not only, different people, different tastes. Plus what attractive changes over time, like till recent years "thick thighs" were not something popular.