"Chocolate moose" is a pun on "chocolate mousse", the pudding.
It is like saying "My hair is getting grey and my waist is getting thick. The solution to both is the same - dye it", which is a pun because "dye it" (for hair) sounds like "diet" (for the thick waist.) That is a pun too.
I had lunch in the rotating restaurant about 2/3rds of the way up the CNR tower, 20 years ago.
Glad I could help, sorry the joke fell flat. Try this one:
A termite walks into a bar. He asks "Is the bar tender here?"
A Sandwich walks into a bar and orders a beer. The bartender says "I'm sorry - we don't serve food here."
A Scotsman, and Irishman and an Englishman walk into a bar. The bartender says "What is this - some kind of joke?"