How do you actually say that? With a mild stutter?
z-zap?
ZZZZap?
You have to bring your front teeth together and then push with your tongue for the "z" sound. Then you end with an explosive "p", forcing air from between your lips. Its a sensual choice of a user name. Its pregnant with possibilities.
The "Captain" bit is like lingerie. Unnecessary but good for a bit of a tease.
Zzap! Zzap!
I bet it makes him feel dirty, to say it out loud. None of his real life friends would know his internet user name is the sound a car battery makes when attached to his nipples.