Answer:
What bow can't you tie.
Some are clean and some are dirty, but all are meant to get a chuckle. Most like it, some takes offense from it.
What do you get when you combine Brazil nuts, Chinese chestnuts and American beech nuts?
If farts are yellow, what color is your burp?
Why did the man throw the butter out of the window?
I am a shimmering field that reaches far. Yet I have no tracks and am crossed without paths.