My worse one. I'd booked a job with a lady after cleaning a doctors surgery, she was the practice manager and lived about a mile out of town. After setting up she said she was going to walk in and get some shopping, see mother and then be done. It was a lovely day, she showed me where the tea/coffee etc was and insisted I made one whilst she was away. I waved her off and knowing the job would take 3 hours wasn't in the least concerned. Just about to start I realised i'd left my polystyrene blocks in the van, went out to get them, and as I got near the van bang! Turned round and the door had shut behind me, gear inside, me outside

It only takes a woman 4 hrs to 'pop into town' and walk a couple of miles. I tried climbing the fence in the hope the patio doors were open. Only to end up with splinters. Garage door locked. Tried the neighbours, no spare key. Stuffed. As she trotted up the drive she was 'delighted' to see i'd finished. Finished I haven't even started! I felt a right T*T. She thought it was rather funny and mentioned even when the door was on the latch it could sometimes lock :

Still (started &) finished the job, hubby had a good chuckle and I still do work for them but it STILL comes up in conversation 7 years on.
Simon