on the bum
Not working correctly or properly; out of order; broken. My car has been on the bum ever since I let my brother borrow it for the weekend. I think our washing machine is on the bum—these clothes are all sopping wet and don't smell clean!
on the bum
see under on the blink.
on the bum
travelling rough and with no fixed home; vagrant. North American on the bum
1. Living as a vagrant or tramp.
2. Out of order; broken.