Others don't get excited until you bust out the rope and riding crops.
If your partner identifies in one of these ways, it's best to ask before touching at all.
14 Tips For Sexy Breast Play
If your partner makes a clear noise, then you have the info you need.
Description: If your partner is really into nipple play, try using a free hand to mimic the motions your mouth is making, using your lips on one nipple and your hand on the other.