A Wet Sense of Humour?

Jared and I usually have our little chats during the drive to school in the morning and it was no different today. I reminded him of Chinese tuition at 3pm and he grumbled.. 'Why didn't you tell me earlier? I haven't done Ma Lao Shi's homework..' my maid obviously forgot to pass on the important message. Then we switched topic to his new Geronimo Stilton books...

Jared: Why do you spend so much money and keep buying GS books? I bet you haven't even READ any of them?
Me: I read Karate Mouse

Jared: You did??! Mr. Han (aka GS' Karate instructor) is very funny right? Serious face.. happy face.. angry face.. (identical expression depicted in the drawings)
Me: Yeah.. the writer has a dry sense of humour
Jared: Mummy, do I have high humour?
Me: Huh???
Jared: What's humour?
Me: Something that's funny.. it makes you laugh..
Jared: Do I have wet humour?
Me: (Laughing).. NOOooo, you have DRY humour.. Quick! Get off now or you'll be late for school!