Oh!  Yeah, I used to get those a a kid.  I'd never  heard of them being called verrucas before.  Is that where Verruca Salt In Willy Wonka's Chocolate Factory got her name?

Verruca must be more common UK term i suppose, funny, i was just thinking of Verruca Salt too, maybe thats an old cure 

What is a verruca?  Is it like a boil?

Warts really and are fairly common among children usually picked up from swimming pools, school changing rooms etc, reckoned to be a virus linked to HPV. They can be a bugger to get rid of using allopathic methods though.

more info here http://en.wikipedia.org/wiki/Plantar_wart

I had a nasty splinter in a finger that was too painful to get out with a needle (wimp that i am) and did the same trick and next morning enough of the splinter popped out for me to get the tweezers on.
should work for drawing poisons out of wounds too, i think its down to enzymes in the banana skin having a powerful drawing action.