Tugging how? Like pulling back while latched on and then looking around? Just pulling back without unlatching but still sucking?
The former: This is kind of a developmental/temperamental thing, I think. One option is to unlatch the baby and end the feeding (knowing that you'll have to feed again shortly) to teach your baby that nursing time is for nursing, not for goofing around. Another option is to feed in a room with absolutely no distractions (I know, I know, totally impossible). Right now, my daughter (5.5 months) pretty much only nurses in our bedroom. She won't even latch on in the living room, which I think she considers the hub of all activity.
The latter: I've heard that this might make the milk flow faster, and I've caught my daughter doing it before. Although it's a little uncomfortable (for me, might be far more uncomfortable for you), I let her do it. Since she's so distractable now, I just don't care. I'd rather she get a full feeding in. YMMV
My 6 month old does that and i'm not sure why. In any case I say no, that hurts with a big smile (sometimes forced
) and he ususally looks at me, smiles back, stops tugging and continues nursing. I realize that this may not work for all babies, nothing except taking my first son completely off the breast worked for him. different strokes for different folks.