These may stop people uttering jokes (4)
I believe the answer is:
gags
I believe this is a double definition.
'these may stop people uttering' is the first definition.
(gags stop people talking)
'jokes' is the second definition.
(I know this)
(Other definitions for gags that I've seen before include "Muffles with slangy jokes" , "Jokes; chokes" , "One-liners" , "Prevents from speaking the jokes" , "Jokes - silences" .)