"To take a man's watch is to flimp him, it can only be done in a crowd, one gets behind him and pushes him in the back, while the other in front is robbing him." --Brandon, 1839. Poverty, Mendicity and Crime.
"flimp - Noun. A taxi driver's term for an unbooked customer or fare. Also flimping, the act of picking up such a fare. E.g.'I picked up a great £80 flimp to East Midlands airport, and they tipped me £10 as well.' South Wales/Leicestershire/Midlands use Verb. To pick-up an unbooked fare. See noun, above. E.g.'I flimped a couple of gorgeous girls on the High Street.'" - peevish.co.uk