Had another minor argument today ... this is about a thermometer that remembers minimum and maximum temperatures. To clear the memory, you press reset. Pressing min (or max) twice returns you to the ordinary temperature.

"Can I press the min button?"
"Er, yes ..."
"It says zero!"
"That was last night's minimum. Press the reset button so we can find out tonight's"
"I pressed min again! See, it says six again!"
"That's just the current temperature, press reset"
"I already pressed min!"
"Can you press the reset button then?"
"But I already pressed min!!!!"

Ugh. I just took it off her and did it for her and showed her that now the min, max and normal temperatures were all 'six'.