Did this one once at a restaurant. All it takes is a drink (with a straw) and a bottle of Tabasco sauce. The ability to keep a straight face is highly recommended. It may take a cohort too, If your unsuspecting person doesn't leave the table.
When your victim, uh I mean unsuspecting target, is away to the restroom put about 4 drops of Tabasco sauce down their straw. This is when a colleague might come in handy. if you can have them distract them long enough.