It's when you insert a balloon in the girl's anal gland and inflate under high pressure. It is very painful and pleasuring. Often times done with helium for lasting effect.
My boyfriend did this to me...AMAZING ;) Except I couldn't walk for a few days and it got stuck in there.
Chat with our AI personalities
When someone is "blowin up" a girl, it typically means they are calling or texting her frequently and persistently. It could indicate interest, but excessive communication can also be viewed as intrusive or overwhelming.