En bak vs ei rompe
I've come across these two terms in one of these Memrise courses and both were categorized under "a butt" translation. However, The "butt" translation shows up in most dictionaries almost entirely only under "rompe" expression. "bak" is translated in most cases as "behind".
So, what do these terms refer to (and, if they refer to the same thing, what's the difference and in which particular situation should I use the respective term)
Any help appreciated!