OK, if your brother can take it as well as dish it out...
Take him to Whispering Canyon Cafe at Wilderness Lodge (PS recommended any time). Disclaimer: Not all the servers are into the "antics"; ask at the check-in station to be seated with a server who is into the fun. This doesn't guarantee it, but it could help.
What to try:
1) Ask your server for ketchup (this may be only slightly embarassing for your brother)
2) Ask where the bathrooms are located
3) Ask the server where their six-shooter is (never use the word G-U-N)
4) Ask the server for directions to Universal Studios
5) Wear a shirt, hat, etc. from Universal Studios and loudly talk about the GREAT TIME you had riding Spiderman, Jaws, etc.
6) Ask where you can buy GUM at WDW
7) Have your brother ask if he can participate in the Pony Express race.
Any or all of these may result in some fun antics. It's not guaranteed -- just like 50's PTC servers are not all into the fun -- depends on the person and the party.