To go for a mountain or downhill bike ride. Expression popularized by cyclist/youtuber Robin Moore with his song "Get dirty".
Al: Julien, do you want to get dirty tomorrow morning?
Julien: No, sorry Al, after today's harmfest I'll do a cool recovery ride on my roadbike tomorrow.
by realfast August 16, 2010
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"Getting dirty" is a term in which relates to a creative sexual activity.
-Wow that couples' so close compared to a month ago!

Yeah, they must have been getting dirty lately...
by Outstanding_oodleN June 27, 2014
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When you and your comrades get down and roll around in communist dirt or mud.
If you’re clean, you need to get down get dirty or else you won’t end up doing The Ambulating Monkey with your comrades!
by Pweaw July 8, 2021
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When the IRA came to your door to do a kneecapping, they'd tell the person to get their dirty jeans on so they wouldn't ruin a clean pair.
IRA: Get your dirty jeans on
MAN: Shit
IRA: Looks like we're good to go.
by CRMCI May 27, 2008
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getting it on; having sex; getting down to business; revealing somebody's personal info to do damage or put them down.
"Those two were getting downa dirty on the dance floor."
"When they were rappin', they started getting down and dirty."
by free_me July 6, 2006
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anyone who gets on their knees to preform oral sex on a male
yo you been around the block. you be getting your knees dirty.
by Tazmanian devil May 19, 2006
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