Readers of my newspaper column wrote me about these dog tricks; hope these folks contact David Letterman:
1) A dog named Sampson, who when asked to "Do Sinatra," croons - "whaoo-whaoo." The owner of the dog say the giddy response proves women still swoon, even with a canine Sinatra.
2) When a Collie named Lassie (of course) is told "search for Timmy," the dog promptly runs off.
3) From Trupanion's (pet insurance company) website. A dog named Tequila. The owner says, "Give me a shot," and the dog delivers a kiss.