Hrmn... well not a cordless phone.... I did drown my mobile in a bucket of bleach water at work though. Needless to say it didn't recover.
My mum did manage to melt out landline (cord) phone on the top of a cooker once. It was rather pathetic really..... we had an old stove with a grill ABOVE the hob, and one afternoon while making dinner, mum got a call...... she dragged the phone through to the kitchen and put it on top of the grill. And forgot it. It started to bubble away quite happily up there on the stove, the smell of burning plastic filling the room (and the food) and then it started to ring!!
"BRRRRRRRRRING-BRING! BRRRRRRRRING-BRingingn Brginnngn -brbr--b---------------bip."
The last words of the household telephone.
She ruined a perfectly good phone. AND a perfectly good cooker. All at the same time!