I can think of two things:
1. Stonehenge. Nice area and everything, and the historical significance of the place is definitely there, but as a monument it is a bit ... disappointing. If you see it anywhere on photos, you'll notice that more often than not it's photographed from below, to make it look bigger.
2. Turkish ice cream. Sounds random, but before I went to Turkey, I got inundated with "OMGWTF, you have to try Turkish ice cream". It's awful. It's a rubbery substance with little taste whose only redeeming quality is that you can do stupid tourist stunts with (due to its rubbery nature). Much better than Turkish ice cream: Turkish beer ("Efes").