The Duddon Valley campsite - Turner Hall Farm - just up the road from Seathwaite in the Lake District. Good pub, the New Inn, just down the road, basic facilities, but a nice field with rocks in, great views and it's much, much quieter than the Ambleside / Windermere / Coniston side of things even on Bank Holiday weekends.
Someone's vegetable patch in Bolivia on the final day of the Illampu Circuit trek, when we ran out of daylight and had to just stop, anywhere, and put up a tent. Ever tried stealth camping with an MSR XGK, the original 'I'm a Jumbo jet coming in to land' flame-throwing expedition stove? Interesting.
Also, the spot beneath the Calzada Pass in Peru where I put up the tent, solo, as it got drk and woke up overshadowed by a wall of snow-capped peaks - superb.