James was walking down the road one morning when he met his friend Danny.

James was walking down the road one morning when he met his friend Danny.
"Morning, Danny. Er ... Danny, you're wearing a glove on one hand and none on the other. Did you know?"

"Yes, well I heard the weather forecast this morning, you see."

"The Weather forecast?"

"Yes, the weather forecast. the forecaster said on the one hand it might be fine but on the other hand there might be some rain."

(Cantonese students have problems with "on the other hand" because there is a similar expression in Cantonese that means "in addition". This joke helps highlight the contrast implied.)