“What job did the frog have at the hotel?”/“Bell hop.”

One popular hotel riddle is:
 
Q: What job did the frog have at the hotel?
A: Bellhop.
 
The joke has been cited in print since at least 2004.
 
   
Google Books
The Gigantic Book of Riddles
By Jacqueline Horsfall, Lori Miller Fox and Joseph Rosenbloom
New York, NY: Main Street
2004
Pg. 48:
What job did the frog take in the resort hotel?
Bell hop.
 
Yahoo! Groups—Puns of the Day
Animal Jokes 01-16-06 Frogs & Toads
Stan Kegel
Jan 16, 2006
ANIMAL JOKES OF THE DAY 01-16-06 FROGS & TOADS
(...)
What was the frog’s job at the hotel?
He was the bellhop.
 
Twitter
El Valor
‏@ElValorSchool
What job did the frog have at the hotel? Bellhop! #KidsJokes #ClassroomJokes Credit: Arseniic on deviantart
3:01 PM - 15 Aug 2014
 
Twitter
Kathy Baseball
‏@KathyBaseball
Hey @TheEllenShow, what job did the frog have at the hotel? Answer: BELLHOP #ClassicJokeFriday
2:44 PM - 8 Apr 2015
 
Twitter
Kim Mauldin
‏@RealtorShark1
#jokeoftheday What job did the frog have at the hotel?
9:01 AM - 20 Apr 2015