吹口哨

吹 = 口 + 欠 : Chantal Chicken (chu) is totally crazy about creating wind instruments from vegetables lately. In front of the Eiffel Tower (ei1) she stole a mandarin (口) from a local merchant and left an IOU note (欠) instead. She carved the mandarin out and created a little ocarina out of it, which she plays by blowing (吹) into it every since.

Mnemonic symbol: 口 shall be represented by a mandarin. Karl Marx (k-) is enjoying a mandarin in the outhouse's living room (ou3).

哨 = 口 + 肖 : The little prince (肖) took a part time job working as a sentry (哨) for Sherlock Holmes (sh). In the aortas's bathroom (ao4) he whistles (哨), thereby giving the secret signal to Sherlock. Sherlock answers by holding up a mandarin (口), which is the secret signal of acknowledgement.