A riddle about bullets is: 
   
Q: What happened when the two bullets got married?
A: They had a BB.
     
“BB” sounds like “baby.” The joke has been cited in print since at least 1972.
   
     
Wikipedia: BB gun
A BB gun is a type of air gun designed to shoot metallic ball projectiles called BBs (not to be confused with bearing balls), which are approximately the same size as BB-size lead birdshot (0.180 in or 4.6 mm in diameter).
 
Newspapers.com
3 April 1972, Charlotte (NC) News, “Mini Jokes,” pg. 3C, col. 1:
What happened when the two bullets got married?
They had a little BB.
Laurie Heinz. Charlotte
   
Google Groups: alt.fan.cecil-adams
Well, Now You REALLY got me going…..
Charles Dimmick
Sep 17, 2009, 11:30:32 AM
(...)
Two bullets got married and one gave birth to a BB.
       
Twitter   
Don McBride
@dirmfe
Q. What happened after the two bullets got married?
A. They had a little BB!
#dmcbqa
9:57 AM · Apr 7, 2011·Hootsuite
     
Twitter
Patilynn Williams
@Patilynnw
What happened after the two bullets got married?.... They had a little BB!
8:08 PM · Sep 20, 2011·Twitter Web Client
   
Twitter
Clifford Hall
@topgunz169
Q. What happened after the two bullets got married?
A. They had a little BB!
6:01 PM · Sep 18, 2015·Facebook
 
Reddit—Jokes
Posted by u/Kangar August 25, 2018
What happened when the two bullets got married?
They had a BB.
COMMENTS
Csylvan135
They banged first right?
 
Reddit—Dadjokes
Posted by u/chipperxyz February 7, 2021
What happened when the two bullets got married?
They had a BB
COMMENTS
MrsBunnyPants26<?i>

I heard it was a shotgun wedding
 
Reddit—Cleanjokes
Posted by u/chipperxyz February 7, 2021
What happened when the two bullets got married?
They had a BB