A condom: Mixture of "bong" symbolizing the akward sound made in cartoons when a male gets a boner and "ker" which is a wanna-be-cool suffix that is supposed to mean "cover" .
Cover the Boner = Bonker.
Dude # 1 - I got a huge boner the other day but my date wouldn't give in... Something about not liking diapers?
Dude # 2 - Your an idiot ! You could've just put on a Bonker !