"Shaking like a shitting dog" is one that always strikes me as being bang on in descriptive terms.
From Diary of a Mad Housewife:
"Don't you ever use the shoebox full of immies you have for a brain?"
I discovered today that an immy is a marble; it was almost better not to know.
"Sticks like shit to a blanket"
"Goes like shit through a goose"
"Hanging around like a spare prick at a wedding"
Used on these very threads: 'If brains were Semtex, she'd still be allowed on a plane'.
Mad as a box of stereotypes denigrating mental health issues.
Mad as a cut snake.
Oh no, a turn of phrase that's cruel to a reptile.
Peter Kay's "Sweating like a paedophile on a bouncy castle" is evocative. Sorry to any small bean regarders out there.