To do something nice (esp. wonderful) for one's girlfriend, spouse, ho, etc., especially where the thing done is considered of high value by the recipient. The saying can be used both literally (as when administering a fix or donating the dope with which to do so) but is perhaps more often used figuratively (as when doing something considered nice).

Similar to "smacking oneself up", as in giving oneself a much needed fix, a reward fix, party fix, etc. To "smack up" someone, then---while not necessarily implying a positive motivation for the act---is usually considered a favorable act. And to smack one's bitch up is considered especially charming and gentlemanly, usually leading to some sort of reciprocity by said bitch.
Bo: Yo, Jim, I'm gonna smack my bitch up with these flowers and candy when I get home, so maybe I'll get lucky tonight.

Rufus: It cost me a couple of Jeffersons to smack my bitch up last night, baby, so don't get stingy on me tonight.
by Wayan October 10, 2007
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It just means "modify my car."
I'm having the mechanic smack my bitch up.
by Janky Rolo April 12, 2005
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Back the Fuck Up Before You Get Smacked the Fuck Up - A Term Or Sentence used when someone has done something wrong or has fucked up. Or when they are obnoxious.

1. When You talk to much
2.When you forget to pay a pimp
3.Fucking with people.
4.What the hell is wrong with you?
Bob: Hey yo ted wheres my money Nigga?
Steve: You Better back the Fuck up before you get smacked the fuck up bob
by Tech581 September 23, 2009
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When you say something wrong, stupid, or threatening, and get threatened.
Jeff: yo girl is ugly asf
Ethan: better back the fuck up before you get smacked the fuck up g
by ezra24 April 3, 2023
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To get physically beaten up. Outclassed.
It was known in the Boxing circle that Anthony Joshua got smacked up in sparring prior to his upset loss to Andy Ruiz.
by ABEL ABE April 16, 2021
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