Asking a hairdresser for a cut but when go to pay being charged for a cut and restyle.I haven't seen an official line , but here are some examples of what I would call a rip-offs:
1) Big sign outside fast food place, burgers €1 .... eat a burger and get asked for €2
2) Car advertised as leather seats... but has plastic seats...
3) Petrol station that charges you for 15 liters of petrol but pump only actually gives you 10 liters....