[ErroneousBosh]

Two things I have found that absolutely positively freak the shit out of my bank:

Buying a full tank of gas and then a full tank of petrol (dual-fuel vehicle) in two separate card transactions one after the other. Can't use the same pump, annoyingly, at least with the old system in Morrisons. Don't know if it's different since their petrol stations have been bought over by Motor Fuel Group.

Similarly, buying a full tank of gas at Morrisons in Bradford where the supermarket chain's headquarters are, then driving five hours north and refuelling again in a different Morrisons which show the transaction as coming from their banking systems in Bradford but tagged as a city in Scotland. This is apparently because it's implausible to drive from the central England to central Scotland in a few hours, and then need to refuel.

They are (or was at least, last checked a year ago) 100% repeatable.