[Fightin Whitey]

Old rancher had a bunch of handpainted signs on his front gate, mostly anti-Obama stuff these days and some old Bircher/anti-CFR slogans, etc.
‘
One of them turned up one day, said:

Q) Why is aspirin white?

A) Because it works!

[Nowhere Man]

Here's one of my favorites:

Q: Why are there no white M&M's?

A:Because they would enslave the black M&Ms, steal all the red M&Ms' land, hunt the blue M&Ms to extinction, accuse the yellow M&Ms of obstructing trade, start a panic that the little green M&Ms were invading Earth, and complain that the brown M&Ms were taking all their jobs.