What have you done, or what do you know about, that is really cool/exciting?
A famous (or infamous) example would be the running of the bulls in Pamplona Spain. Not exactly my cup of tea, but you get the idea.
I haven't been to Burning Man
but I hear it's a blast.
Maybe the Westcoast Trail turns you on. A California racing school? Rafting the Amazon? Hang gliding in the Alps? Cave diving in ... wherever there's cave diving?
Perhaps you're a masochistic nutbar who gets his jollies by riding to the Arctic Ocean ... whatever floats your boat.
Please be specific, that is, instead of "African safari" tell us about the safari from A to B during rhino rutting season, or some such thing.