Ice fishing

A young man went ice fishing, but didn't catch a thing all day.

He noticed a old fella in the center of the lake pulling fish after fish out of the pond.

He went to the old guy and asked him "What's your secret? How are you catching so many fish?"

The old man looked up and replied "Mrrrhrrr mrrhrr mhrrwwrrmm wrrrm"

The young man said "What?"

"Mrrrhrrr mrrhrr mhrrwwrrmm wrrrm"

"Sorry?"

So the old man turns and spits "Plaugh!", then says

"You've got to keep your worms warm!"