a term coined in the tv show New Girl which means a person who is in a state of sadness or depression and due to this, goes back to their ex.
Ashley: OMG, did she just get back with her douchebag ex-boyfriend?
Rachel: Yeah but only 'cause she's been super depressed lately.
Ashley: So she backslid to her ex?! What a backslider!
When you are walking down a road approaching a very hot chick and want to know if her ass is as hot as her face. As soon as you walk past her you turn a full 180 degrees in order to creep on her ass.
Dude 1: Did you see how hot that chick was?
Dude 2: Yeah man, as soon as I got past her I stuck a perfect backside creep 180 to get a look.
Dude 1: And...?
Dude 2: The view was sensational!
When your doing someone from behind and you pour a Milkshake down their back ; and you don't stop.
I was doing my girl in a fast food restaurant's bathroom, from behind, when all of of sudden I poured my milkshake down her back and I watched slide down. The frosty backslide was invented. we both ended up sticky.