sweet 16

With a few minutes to go before I turn 27, it´s nice to be told I look younger than I am (not that I think 27 is past it, but still...). So when a taxi driver today asks me how old I decide to find out how I´m looking for my age:
"¿Cuanto me dás?" ("What would you give me?")
... long pause ... turns head round to carefully consider the matter...
..... ¿Dieciseis? ie 16!
I assume he is joking and thank him for the compliment. And then repeat the question ¿Cuanto me das?
......¿Diecisiete? ie 17.
I realise he is not joking.
.... Eh, bit more...
.... ?Dieciocho? ie 18. He is looking at me in disbelief now. Oh dear. I think that was a bit of a compliment-too-far.