A blowjob a man gets from his female patner when menstruation prevents the couple from having vaginal sex. Uncle BJ is often a man's only available option for sex from his wife or girlfriend when Aunt Flo comes to visit.
Wife: "You'd better forget about tonight, honey. Aunt Flo's coming for a visit."

Husband: "Well, I hope she brought Uncle BJ with her!"
by trxstr January 01, 2010

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Top Definition
A suitable alternative for sex while your girlfriend/wife is menstruating also known as a blow job. More specifically as a counter to a woman who uses her period (Aunt Flo)as an excuse to avoid sex.
"I don't care if Aunt Flo is in town as long as she brought Uncle B.J."
by Saltine Nachos February 20, 2009

The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Your favorite word on a white mug.

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The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

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The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

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The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt