Nothing, absolutely nothing will happen to you (Unless you bring a bag full of reps, then you might (just might) get into trouble.
Wearing a rep itself is not a crime, and there are certainly no cumstoms or policemen specially trained to be able to spot reps on peoples wrists....
In most cases one would have to be somewhat of an expert to spot our watches as reps, and in many cases you need a loupe
So, wear you reps and dont worry at all!!
// Mike