It sounds more like past tense “sank” which also makes more sense in context of the question.
Some of the more cultural dialects of US English pronounce "sank" with two syllables: like "say-ingk"
"Saink" isn't a bad way to spell it, either.
No I'm with you, as a french speaker, it's also hard to get the joke for some reason.
Two cats named “One Two Three” and “Un Deux Trois” raced across a river, which one won?
It was One Two Three, because Un Deux Trois quatre cinq.