When a girl (or guy if you roll that way) is giving you a Blow Job and they use their teeth instead of their lips to give you a BJ. This can feel good if it is done lightly but usually when you refer to the comb a girl has used a little too much teeth on your dick. Usually inexperienced girls perform the comb quite often until a guy brings it up.
Susie was giving me the comb last night and I didn't have the balls to bring it up with her so I sat through a terrible blow job.
After Susie was finished giving me the comb, she had to peel my dick skin from her teeth.