Slap happy describes a guy who likes to jerk off A LOT - as in more than what is considered normal or healthy.
Dave: "Have you seen Bill around?" Bob, "No, I haven't seen Bill around in a long while - I heard he likes to stay in and slap his slap-stick around all day - I'm afraid he's gone slap happy!"
Slapping the hands together as though you are happy and high on life for what you are doing at the moment, or what you are planing to do in the near future.
I'm slap happy because we are going to Mc.Donalds. Mc.Donalds is a "Slap Happy " place.
When a man takes his dick out if a woman's vagina so he can pleasure the woman's vaginal area by slapping it. This usually resukts in a truckerorgasm, the loudest and happiest orgasm one can achieve.
Taking my penis out of my wife's vagina, I promptly gave her an unexpected trucker slap, and she screamed for so much joy!
When a sophomore douchebag slaps the back of an unsuspecting freshman's neck.
Bro WTF happened to your neck
I got wangtang slapped bro
To shatter someones masculinity in some way or another.
For further reference, see "Don't be slappin' my penis" by Kollektivet on Youtube
Examples of Slapping someones penis:
Nurse: "I am sorry sir, but you have testicular cancer"
Mother:"You forgot your helmet, son"
When you jerk off onto the back of your hand, and bitch slap the shit outta someone
Max: This bitch talking mad shit right now!
Brandon: Go to the bathroom and hit her with the peruvian pimp slap.
when in the sea and a wave hits you in the face
A: Oh dude, can you see that huge wave coming?
B: What?
B turns around and wave 'slaps' him in the side of his face
A: LOL dude you just got sea-slapped badly!!!!!!!!