Not really funny (ish) but memorable. We had quite a big garden and once a year had a massive tidy up followed with a bonfire. All the wood went in a pile, all the weeds from digging the garden, more wood and burnable junk from the garage, then my Mum had junk that would burn, loads of card board, old paint tipped out, old bottles of oil, you name it, it went on.
This bonfire stood 5+ feet tall with a load of branches after tree pruning to add to the fire. Realising he should have built the bonfire over the braches to let the air circulate to ignite the fire he decided to use an accelerant - Petrol.
He poured/sprinkled petrol over the bonfire and well dowsed the base, ran a trail to the shed, happy with the preparation he double checked, plus checked his route to the back of the shed as the fire took hold.
Anyways, he lit the petrol trail and whoooooooooooosh up went the flames and what must have been a combination of heat build up and explosion he was pushed/thrown into the shed and the whooosh of the heat came into the shed and threw the door shut, so my old man stayed in there and lit a fag while the fire settled.
When he came out of the shed 2 mins later a few of the neighbers were searching the garden looking for him, he was howling with laughter , but then realised how serious it was when they told him a big cloud of black smoke rose into the air in a mushroom shape like an atom bomb going off.