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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everything goes smoothly through out the day, no bullshit or drama
dick: man today was fuckin gay bruh
master: ha sucks because i just made today my bitch
by damn white boy July 10, 2010
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If u just got someone really good or need them to understand how much of nothing they are, this is the phrase to use. Best if used against Chirish or people named Daniel Tim.
(after slapping upside the head or on the nipple) You my bitch! Suck it dry!
by RespectMeBitch September 21, 2004
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That one fucker you're stuck with for the rest of your life because they know far too much for you to just be casual friends
Much like a parasite you are one in the same being except a main bitch has better taste in movie trivia
by Salimas-main-bitch June 20, 2016
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A bitch who has one or more of these traits:
1. Steals all her boyfriend's money
2. Hates everyone, but expects everyone to like her anyways
3. Very stuck up
4. Displeasing to the entire female population (this includes animals) and emits a rancid odor detectable by most
5. Gets her boyfriend way too whipped

Abbreviated: MSB
Alicia and Bethany are my sized bitches. I feel sorry for Ben and Nathan (respectively).

and

I contain no MSB
by Mr. Tap July 13, 2004
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