An Uncle Sam riddle is:
 
Q: What’s red, white, black and blue?
A: Uncle Sam falling down the stairs.
   
“Red, white and blue” are the colors of the American flag and also the traditional dress of Uncle Sam. When he falls down the stairs, his body is “black and blue.” The Uncle Sam joke has been cited in print since at least 2011.
   
     
Twitter
Walter G
@Waltie1Meow
What is red, white, black and blue?  -Uncle Sam falling down the stairs
10:49 AM · Jul 3, 2011·Twitter Web Client
 
Twitter
Ivy Picklebottom
@IvyPicklebottom
What’s red, white, black and blue? Uncle Sam falling down the stairs! Happy Independence Day to all my American followers.
12:35 AM · Jul 4, 2011·Twitter Web Client
 
Twitter
Brandon
@brandonboet
What’s red white black and blue? Uncle Sam falling down the stairs… haha
4:45 AM · Jul 4, 2011·Twitter for BlackBerry®
     
Google Books
The Super, Epic, Mega Joke Book for Kids
By Whee Winn
Grand Rapids, MI: Zonderkidz
2016
Pg. ?:
What’s red, white, black, and blue?
Uncle Sam falling down the stairs.
   
Reddit—Jokes
Posted by u/JackPEvans July 4, 2018
What’s red, white, black and blue?
Uncle Sam falling down the stairs.
 
Twitter
WD53
@watchdog53
How come there’s no Knock Knock joke about America?
Because freedom rings.
 
What’s red, white, black and blue?
Uncle Sam falling down the stairs.
12:18 PM · Jul 3, 2019·Facebook
 
Gadget Freeks
Happy 4th of July 2019: Memes & Funny Jokes to share on USA Independence Day
Published on July 4, 2019
By Mary
(...)
What’s red, white, black and blue?
Uncle Sam falling down the stairs.