Seems more related to bad parenting than condoms to me
Agreed. But thats part of the cleverness of the commercial - it ties two more or less unrelated things together and sends the message that one causes the other.
but oh that ending... ouch
Advertising is all about evoking an emotional reaction (positive or negative), and then tying that emotional reaction to the product. So in this case, they were able to take the negative emotional reaction to getting hit in the nuts (which is something that every guy can relate to), and tie it pretty powerfully to something that really is almost entirely unrelated.
Agree or disagree with the connection they are making, you cannot deny the emotional charge it has, and therefore its both clever and effective.