When a male/female has sexual relations with a friend's boy/girlfriend.
"I think my friend is back dooring me, I saw his boxers in my girlfriend's covers the other day!"
by DellyWasHere February 28, 2012
1 more definition
The act of putting yourself in a position that furthers you from your optimal goal. Doing something even though you know that it is not helping you in life and instead it is holding you back.
I'm really backdooring myself... I failed a test because instead of studying the night before I went out and got wasted.
by the bbbear July 17, 2010