A popular Christmas riddle based on the Cherles Dickens story A Christmas Carol> is:
 
Q: Why does Scrooge love Rudolph the Red-Nosed Reindeer?
A: Because every buck is dear to him.
 
The joke has been cited in print since at least 1998.
 
“How did Scrooge win the football game?”/“The ghost of Christmas passed!” is another Scrooge riddle.
   
     
Wikipedia: A Christmas Carol
A Christmas Carol in Prose, Being a Ghost-Story of Christmas, commonly known as A Christmas Carol, is a novella by Charles Dickens, first published in London by Chapman & Hall on 19 December 1843. The novella met with instant success and critical acclaim. A Christmas Carol tells the story of a bitter old miser named Ebenezer Scrooge and his transformation into a gentler, kindlier man after visitations by the ghost of his former business partner Jacob Marley and the Ghosts of Christmas Past, Present and Yet to Come.
   
Google Books
3650 Jokes, Puns, and Riddles
By Anne Kostick, Charles Foxgrover and Michael J. Pellowski
New York, NY: Black Dog & Leventhal Publishers, Inc.
1998
Pg. 456:
Why does Scrooge love Rudolph the Red-Nosed Reindeer?
Because every buck is dear to him.
 
2 December 1998, Indianapolis (IN) Star, “B&B show more family friendly” (review of “Christmas Spectacular” at Beef & Boards) by Marian Garmel, pg. E5, col. 2:
But most of their jokes, meant to be lampoons of corny vaudeville jokes, are simply groaners. Why has Scrooge been sending fan mail to Rudolph? Because every buck is dear to him.
   
12 December 1998, Edmonton (Alberta) Journal, “On Your Life; News tips, how-tos and other stuff,” pg. F1:
Why does Scrooge love Rudolph the Red-Nosed Reindeer?
Because every buck is dear to him.
 
Google Groups: alt.med.cfs
Cristmas one liners (for ERIN) ~~
Ken Coleman
12/21/99
(...)
Why does Scrooge love Rudolph the Red-Nosed Reindeer?
Because every buck is dear to him.
 
Google Groups: alt.humor.puns
“Puns of the Weak” 12/22/00
Stan Kegel
12/23/00
(...)
Why does Scrooge love Rudolph the Red-Nosed Reindeer? Because every buck is dear to him.  (Kegel Archives) 
 
Twitter
Rich
‏@MintMickey
RT @DisneyFrankness RT @FizzyBear: Why does Scrooge love Comet the reindeer? Because every buck is dear to him. Wacka,Wacka
1:12 PM - 22 Nov 2009
 
,a href=“https://twitter.com/hyppychick/status/6375253468”>Twitter
Amanda
‏@hyppychick
Why does Scrooge love all of the reindeer? Because every buck is dear to him! #fb
12:05 PM - 5 Dec 2009
 
Twitter
Susan Springfield
‏@SusieSprinkle2
Why does Scrooge love Rudolph the Red-Nosed Reindeer?  Because every buck is dear to him.
10:44 AM - 7 Dec 2009
 
Google Books
The Mammoth Book of Really Silly Jokes
Edited by Geoff Tibballs
London: Constable & Robinson, Ltd
2011
Pg. 141:
Why does Scrooge love Rudolph the Red-Nosed Reindeer?
Because every buck is dear to him.
   
Google Books
Funny Christmas Dad Jokes
By Peter Crumpton
PeteyRF Creative
2015
Pg. ?:
Why does Scrooge love all of the reindeer?
Because every buck is dear to him!