Choke on a joke (3)
I believe the answer is:
gag
I believe this is a double definition.
'choke on' is the first definition.
(thesaurus)
'a joke' is the second definition.
(a gag is a joke or witticism)
(Other definitions for gag that I've seen before include "A palindromic joke or muzzle" , "Muzzle in palindrome form" , "Silence the joke" , "Stifle; joke" , "Retch at the joke?" .)