This saying is used to
peer pressure others into doing bad activities, such as drugs,
pooing in front of others, or drinking another
dude's piss. However, it sounds so retarded that it can only be used ironically, and my friends and I often use it in a very joking and ironic context, encouraging each other to do absolutely retarded shit by chanting "do it and you're cool"
Dave: You should do drugs and
eat poo on the balcony
Tomas: What the fuck? In Hungary, drugs are punished by horse archer
firing squad, and I don't want that fate
Dave:
Do it and you're cool