How abour a 200ml bottle of urine and a leaky cap? Unscrew it a bit more when you hand it over.
Alternatively, I wonder if anyone will decide to make a b*mb to target the security desk. Just think, leave a bottle of shampoo at the security desk that blows up an hour later, taking the security area, staff and passing crew with it. Presumably if it is not safe to go airside then it is not safe to be in the terminal.
Please, please, please tell me that they don't confiscate things that are too dangerous to go airside and then just leave them in security????? I see they display a clear box of confiscated items at LGW.