It's funnier when you know that it's not even their joke xD The dub actually had Vegeta say "hmph... he's been disarmed" with a smirk on his face, and TFS was just referencing that.
Uh... You can't call it NTR or cuckolding in this case since it was a dude fucking a child in front of their mother... Unless the mother is in incestuous pedophile.