What is the pun in this joke?
Clowns divorce. Custardy battle
by Simon Munnery
When a couple divorce, there is often an argument over which parent gets to have their children live with them. Having responsibility for the children in this situation is called custody and hence the debate is known as a custody battle.
However, clowns (comedy circus performers) often have mock fights, in which a food substance known as custard is thrown around, often in the form of pies. Such a fight might be known as a custard-pie fight. However, a fight can be called a battle so it could also be referred to as a custard battle. You might describe the battle as 'custardy' i.e. involving custard.
So when clowns fight, you could describe it as a 'custardy battle', which is a pun on 'custody battle', which you might get when clowns divorce. 'Custardy' and 'custody' will generally sound the same when spoken.
The joke is about the word: /'kʌstədi/ (British RP transcription).
When you hear the joke, this word might mean to do with custard, in other words the adjective custardy. We can make adjectives like this by adding -y to a noun. So for example, take the compound noun Stack Exchange, we can make the adverb Stack Exchangey by adding this suffix:
Here the speaker is making a new adjective custardy from the noun custard. Custard is a dessert sauce that clowns use in their show. They throw custard pies at each other, for example.
However, /'kʌstədi/ might also mean custody. This is a word we use a lot in divorces. It is about who becomes the legal guardian of the children. We use the term quite loosely, though. For example, we might talk about who's going to get custody of the goldfish!
Ref: photo from: US Daily review. URL