Here's a weird one for you.
Described as "a name for the sort of 'nutter' who sits next to you on the bus and does something weird." (www.geezer.demon.co.uk) by some, this word seems to have its roots in the French phrase for 'window shopping', or just looking at things in shop windows that you can't afford:"lécher les
vitrines". This translates literally into English as "to lick the windows."