Is cosuil gor mheith tu, is gur threigh tu an ghreann...

(It's like you're fading, and failing in funniness...)

From An Mhaighdean Mhara, a song about a mermaid with other wonderful lines, such as "is an sneachta ag frasach ar bheal na h-abhainn" (and the snow pouring down at the mouth of the river [as the mermaid swims there]).

As everyone knows, mermaids are incapable of seeing the humour of things - one of the first symptoms is the loss of a sense of humour. Beware.