Years ago when I worked in forestry I was felling some large sweet chestnut trees. At the base of one tree was a bit of a mound of earth. I didn't bother to look too closely, just started preparing my cuts to fell the tree. Just as I was ready to start the final back cut, I felt something tickling my leg........quite a lot of things tickling my legs in fact

.
Turns out the mound of earth at the base of the tree was a large wood ants nest!My legs and chainsaw protective trousers were crawling with large wood ants. Then they started biting in rather tender places!

I whipped down my trousers to try and find the offending ants........just a a little old lady walks by in the distance walking her dog.
All she saw was some strange bloke standing next to a chainsaw beating at his nether regions
Lesson learnt - always check what you are standing in!