Fun fact (according to wikipedia): The name Thin Lizzy is based on a comic book character named Tin Lizzy. The band, from Dublin Ireland, changed the spelling to Thin Lizzy, however, in a Dublin accent, Tin and Thin are pronounced the same.
I don't know if that means they'd say, "where's the thin foil" or "I need to lose weight, I wish I was tinner," but depending on the answer to that, the contestants MAY have been correct and Alex wrong.