My two best occurences were when a tall young gas worker came to do the annual inspection. Obviously there was alot of bending over to check the vents etc  >:D. Even before he had started, I had been ogling his tight undies through his thin trousers, he was wearing briefs with the outline showing a clear Vshape up the cheeks of his arse. Then came the bending over, the grey waistband of his Next briefs  just down enough to show the hairy area at the top of his crack, with the promise of further delights within. Needless to say, I took a keen interest in his work that day.

The second time, I was waiting to cross the road at traffic lights, there was a telecoms engineer complete with fluorescent jacket and hard hat crouched at a coms box on the corner. His trousers were way down his crack, just a glimpse of his no doubt sweaty undies, and plenty of arse flesh on display, I lingered just long enough without raising suspicion, but it raised more than a smile with me ;D