I have been thinking this for ages!! They always feel the need to either keep their hands warm or play with whatever's down there.
On Chav Watch today I saw one particular chav crossing the road in front of our office, which is a particularly busy road, and he was running across the street (with customary hand down the kex) when he decided to stop and lick his fingers to get a slight smear mark off his otherwise spotless chav-esque trainers (think they were Reebok Classics) - the stain must have been quite stubborn as it took him ages to remove it.....was going to suggest he used some Cillit Bang, but didn't get my head out the window in time....traffic was beeping and swerving, just so this dude could clean his trainers.....I agree with McFroog...their brains must be down there. Wonder if they carry antibacterial wipes around with them to clean their hands every time they stick them down there?