Sit on lap day

Your lap is the top of your thighs when you sit down, where your cat might sit. Lap can also refer to a trip around a racetrack, or to the act of overtaking a competitor by a lap. Lap is associated with a number of idioms. If something "falls into your lap," you have gotten something without making much effort.

"Hey it's sit on lap day"

"Ok go ahead"

sit on a wine bottle

When you're annoyed at someone, and you want them to shove the neck of a wine bottle up their butt so they feel pain and misery

"Go sit on a wine bottle, Mary"

sit on Gray's pipe

A euphemism for a sexual style aka cowboy sex.
Sometimes confused with a morning hard on

Emma asked if she could sit on Gray's pipe.

No problem I'll just lay back then said Gray!

Past tense:-
I sat on Gray's pipe this morning said Emma

sit in his chair

(Russian expression)

In slang, to sit in someone's chair, in Russia, means to 'pimp' out a woman to them

"Hey did you get the cop to get off your back about the murder charge?"

"Yeah, I had my daughter sit in his chair, and they let me go."

sit on the police lap

To "sit on the police lap" is defined as snitching.

The same ones setting it off be the first ones to sit on the police lap.

Flagpole sit-up

The act of attempting to suck ones own penis.

Steve was so embarrassed when his wife walked in on his attempt to do a flagpole sit-up.

sit down skinny

The type of skinny that when you sit down fat doesn't roll at your stomach.

Girl I hate you. You are sit down skinny 24/7.