Funniest walk in i've experienced was many years ago at one of close friends house. We were sat in his bedroom, and my mate had just popped a shotty (for those who don't know what a shotty is, he had just taken a huge bong hit) He cleared it, his old man walked in the door, took one look at his face and the bong in his hand, shook his head and walked out.

My mate exhaled, looked around and said "Guys...did that just happen?"