Overheard last summer -- a couple of perhaps tipsy Yanks were climbing the hill in West Cowes, on the Isle of Wight, re-enacting a version of the classic Abbot and Costello "Who's on first" gag:
Yank #1 stops to catch breath. Suddenly tilts to admires a flowering shrub.
Yank #2 goes, "Oh, that's X. "
Yank #1 replies, "Yeah. No kidding. What do you call it?"
Yank #2, "X."
Yank #1, "Sure. But what I want to know is -- what's the name of that plant?"
The volume escalates as they continue not to understand one another. Finally, Yank #2 says, "THAT'S WHAT I AM TRYING TO TELL YOU!" and the other one goes, "Forget I asked. Let's just get another drink."
[Gardeners probably know already, but I had to look it up. First correct (or entertaining) answer below earns a prize.]