Put uneven inserts in your shoes, or a small rock in one of 'em. I can pick out my dad from 500 yards from his walk.
Wig (a convincing one).
Glasses, or lack thereof if you wear 'em.
Learn a new accent. Know this: Do NOT try British or German. Everyone can see through a bad one in a heartbeat. Try Australian or Russian instead. Cough a lot beforehand for a dry, hoarse effect.
Wear a different cologne/ wear cologne.
Shave the beard, if it's something you're willing to do. Since this is A) deserved, B) elaborate, and C) you're an actor, it should go anyway.
If you are normally quiet, talk a lot; if usually loud, then speak as little as possible.
Don't sleep for at least 24 hours before the joke. Drink a
little (be careful with this one).
Avoid eye contact with the victim.
Use makeup (yes, makeup) to change your skin tone. You're an actor--suck it up.
Develop a false nervous habit that you'd never do in real life.
Chang your hair color to something
lighter. This will help when you change it back, and lightening your hair changes one's look more than darkening it.
That's all I can think of for now...