Um, I believe the literary convention here is to apply the addendum “that I know of”. As in, “I have no kids in CA- that I know of!” thus implying extensive sexual experience (in California).
It can also be used as a rejoinder by changing the “I” to “you”. In that context, Camp says “no kids in CA, bro” and Scotty responds with “That you know of!”. In this case it still implies extensive sexual exploits but in a slutty way.
If used in person- in either context- it should be accompanied by a high five for further humorous effect.
Keep in mind that this is not actually funny. Like a mullet, skiing in jeans or or driving a Pontiac Aztek it is only funny as a form of self-mockery.
"You want your skis? Go get 'em!" -W. Miller