We find out why touch sensitive switches are sensitive to skin, soap and potato but not everything else?  Plus we ask how do drinks &amp; exercise affect the taste of your chewing gum? Like this podcast? Please help us by <a href="https://www.thenakedscientists.com/donate">supporting the Naked Scientists</a>

Why aren't blood donations rejected?

Each week we set out to solve one of the world's weirdest, wackiest, funniest and funkiest scientific puzzles. And along with the answer there's a brand new question to think about for next time...