Go cocky funny on her!, This happens to me all the time, so ive created sum methods to deal with this age situation
HB:How old are u?
Me:Old Enough!
HB:Hhaha
If she says for what? which is rare
say: thats for me to know and for you to find out, (I knw its kind of chessy but hey it worked for me a bunch of times)
U could also try this
HB: You look realy young how old are u?
Me: (age) But im not going to be ur BOY TOY! If thats what ur thinking
HB: HAHA
Me: I think u have me confused with Ashton Kuthcher(this shows that ur up to date with pop news)
Me: from now im going to call u demi more
HB: haha I love her
Me: Realy me too, we can role play strip tease in my place!
HB: hahah (punches arm)