Penis Backfire 

When you strain to cum so hard you shit yourself

"OMG Miley, I must have done something right because just as he was finishing he had a penis backfire and made a huge mess.

Penis Backfire by TMex1971 May 18, 2015

Midnight Backfire 

When you or significant others fart wakes you up in the middle of the night.

My boyfriends midnight backfire vibrated the bed and turned the sheets into a stinky mass of air.

Midnight Backfire by Nana711 November 4, 2014

Cum Backfire 

When in the instance of sexual intercourse, during the backward thrust the penis slips out of the vagina during the peak of ejaculation causing a misfire of semen that spurts onto the male's chest.

My wife laughed at me after my cum backfired on my chest yesterday while having intercourse.

Cum Backfire by WakkaWakka101 June 18, 2010

Cumtucky Backfire

A sexual act involving nutting inside the vagina at the same time as she queefs, blowing the cum back all over the male’s genitals.

Danielle timed up a powerful queef and gave Joe a Cumtucky Backfire that required a lot of tissues to clean up.

Cumtucky Backfire by Goochie Gang November 17, 2019

nostalgia backfire

An event in which someone gets re-acquainted with a favorite song, movie, or other thing from their past, but eventually finds that it only reminds them of the time at which they got back into it.

My junior year of high school, I went up into the attic and found that Super Mario game I used to play when I was, like, 10 years old. But now when I play it all I can think of is how it was the one thing about my high school days that didn't suck. What a total freaking nostalgia backfire.

nostalgia backfire by OneMileFromGlory December 7, 2011

Tennessee Backfire 

when you cum in a girl's mouth and she spits it back at you

Dude, I blew my load in this chick's mouth the other night but then she tennessee backfired

Tennessee Backfire by BoiBlue May 3, 2012

NyQuil backfire 

When upon taking a small to moderate dose of NyQuil or other OTC sleep aids which contain antihistamine as an active ingredient the ingested pharmaceutical produces undesired side affects such as jitteriness and/or increased heart rate which counter the intended result of sleep.
There is no known cure, treatment is focused on achieving sleep. Common treatments include: large quantities of liquor/cheap beer, more of said pharm, marijuana, drugs...

Man I really wanted to sleep before my flight but i had a NyQuil backfire and I was up all night with a dry ass mouth...
Yo I fuckin hate when NyQuil backfires, fuckin stresses you out the whole next day

NyQuil backfire by lostmonster March 20, 2009