To be a flagger. The act of flagging.
To say that you are going to do something and not do it. To get the reputation of being a flagger is not a good thing.
Yo man, i heard you're tryna get with that gerl, don't waste your time, shes a flagger. She's just going to lead you on.. and then move on.
Yo broh, what happened last night? We were supposed to chill but you never picked up your phone. You were flagging nasty!