sack steamer

When a male farts, and the fart travels through his gooch, and then upwards towards his balls. Thus giving him a disgustingly warm and smelly sensation.

Guy 1: Dude, I was sitting down in class and couldn't hold it in my fart anymore so I ended up farting and it gave me a sack steamer.

Guy 2: Ugh man, those feel so warm yet so gross.