Do you have a sweet tooth means do you like eating sweet things.
For example:
Dentist: Do you have a sweet tooth?
May: Yes, I like sweet things very much, especially toffee
toffee [ˈtɔ:fi:, ˈtɔfi:]nclick="document.getElementById.src='http://res.iciba.com/resource/amp3/1/0/57/67/5767192fc6eca8f8d7e5a1ac5a13bd50.mp3'" src="http://www.spiiker.com/js/editer/play.gif">奶糖,太妃糖