when you try to insert both testicles into your partner's asshole. the phrase is referring to the inability to keep a dog in a bathtub, much like the inability to keep both your balls in their asshole.
a) (humorous); what you do when when you come out of the shower and you are too bloody lazy to use either a towel or a blow dryer to dry your hair comme du monde and you just shake your hair all over the place, literally like a wet dog, hence the name
b) (drug addiction) : episodes of literal uncontrollable 'wet dog shaking' characteristic of drug addicts undergoing withdrawal symptoms, especially withdrawal from heroin or cocaine.
mother: Stan, why the hell is the bathroom floor wet again?
Stan: lol, don't ask stupid questions, you won't receive a stupid answer. It's lol because I just did wet dog shakes; I was to lazy to use a blow dryer.
mother: Stan, I hope this wasn't f-sag. Now go take a mop and mop the bathroom floor
1. Originated in Texas, The Texas Wet Dog, is a common sexual maneuver in which a man first performs the pull and pray method during vaginal sex and then commences to bust his nut. A dog, (preferably fuzzy, small and hand held) sits on standby near the area of occurrence, and is used as a means of cleaning up the man's love juice.
2. Other forms include the Texas Dirty Dog, where soon after anal sex, the dog (preferably a German Shepherd) cleans up the excess fecal matter.
John: Want to get your suck on?
Shandra: Yeah! But I'm not sure about the cleanup...
John: No worries, we have Rover for the Texas Wet Dog!