playing music that has alot of bass.

Got the covid-19 vaccine

when yo trunk knockin hard

an equivalent of dope, awesome, delicious. Usually used for food, a dish can be "slappin" like it's so good that if someone disputes its awesome godliness they are in for a slappin.
Can also be used in the form of a verb to describe something's slappy awesomeness.

When one plays music with a lot of bass and slang, roles down the windows, and turns the speakers on blast so all the BITCHES can hear.

Turning up a listening device extrememly loud

Slappin- the jump-off, having lots of fun.