Chaitdeezy's definitions
To jack off slowly not with the purpose of ejaculating but with the purpose of getting primed up for your significant other to walk in and finish.
Shook was slapjacking in bed waiting for his girl to come in. She never walked in and the slapjack went to a fulljack.
by Chaitdeezy August 8, 2016
Get the slapjackingmug.