A quick skip through the gate behind someone else; forcing the barriers open with a brutal shove; skipping through open gangways at the end of the day without tapping your card; or even buying a cheeky ticket that covers only a fraction of your journey.
Fare evasion is a nigh-on endless occurrence on London's transport network, costing Transport for London some £130million each year - or more than £4 every single second.
But with the help of technology, a growing team of professional investigators and sheer determination, the transport body is fighting back - and putting fare evaders firmly in their place.
TfL has some 500 uniformed 'revenue control officers' - alongside an unspecified number of plainclothes inspectors - across the entire network, covering Underground, Overground, buses, DLR, Trams and the Elizabeth Line.
They all have the power to demand proof from passengers that they have a valid ticket, Oyster card or bank card.
