How is it going e+ ? it's been a while ... anyway

So , the other day I was out dinning with some friends on a restaurant (sort of) and then some british tourists started creating a commotion because they did not want to pay I think or they thought the bill was too high ... anyway it's not the reason why I created this topic .

After a few minutes they payed and went out and it was then that they started to show us their naked asses and of course started laughing like telling us "ha ! Take that idiots of the restaurant! " .I can't find the words to describe how bloody ridiculous this gesture seem to me ! It was the very first time I saw this in real life ...I've seen it on movies ,the net , pictures etc but never ever from rl !The f@ck were they thinking ?
Do you know what happened then ?We laughed our butt off because of they gayest event we've seen in a while ! Not just me and my buddies but the whole restaurant!

The reason I post this on this forum is because I know that many people are from different countries and maybe be used to this and if possible can someone tell why do such a shameful deed ? I mean , seriously , presenting your ass in public is like saying " I'm a huge f*g please rape me!!! " . What is it supposed to mean anyway ? How manly is that ha ? I would not presetn this place of my body for loads of money

on a side note , I don't have anything with british people of course ...