Taking a number 2 and a number 1 at the same time while in the bathroom, thus 21 - the perfect bathroom blackjack.
After 2 hours of being on the road, Lyndon had to take a shit and piss so badly, that he blackjacked as soon as he got in the bathroom.
by Poncho23 November 30, 2015
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A word applied for weed measurements. A blackjack is ¾ oz. (21g).

The word "blackjack" is derived from the popular gambling game, which is often called "21".
- Hey pal, I'd like to buy a blackjack.
- Ight, it'll be 100$.

I smoked that blackjack all by myself!!
by Poulin La-Terreur September 19, 2011
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1. Noun: A sex position in which a man defecates on a woman's face whilst performing a "reverse 69."
2. Verb: The act of defecating on a woman's face whilst performing a "reverse 69". In preparation, the man usually drinks a pint of laxative, and then, whilst positioning his penis for insertion into the woman's mouth, instead releases a flood of watery diarrhea into her open mouth and upon her face.
1. Girl, "My boyfriend gave me a blackjack last night."
Friend, "Really? How was it?"
Girl, "Not bad, but I got some corn in my eye."

2. Frat Guy 1, "Hey Bra, remember that time that I totally blackjacked you? That was awesome."
Frat Guy 1, "Yeah Bro! That shit ruled!"
by Captain Hot Pocket October 26, 2008
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Blackjack - Adjective. The slightly more racially sensative way to say that something has been installed incorrectly/poorly or "Nigger-rigged"

"God damn, Tracy. This cable install runs back and forward all through the house. It was clearly blackjacked."
by ©hris April 13, 2009
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when a white guy gets his girl jacked by a black guy
by zdog0850 December 18, 2009
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A word describing someone (usually a female) who is aged 15, as you are unsure wether you can have sex with them.
"she was 15" "as in blackjack?" "yeah" "not sure wether you can hit it?" "exactly"
by wildbill56 March 10, 2010
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