Yes I played chess with one girl once and I must admit, I cheated her. I didn't use any electronic devices, I used another girl instead. Much better, you don't have to go to toilet that often, come out with a red hand and no one will suspect anything.

Now seriously, if I suspected anyone cheating on a tournament, after his last trip to the toilet I'd say "man, you have some serious trouble with digestion, or do you?" and see how he reacts.