This is for a car parked in a bike lane/on a pavement.

What I generally do is just stop behind it and wait for it to go away. If parked on a pavement I sometimes sit on the kerb.

The main problem is getting cold so watch out for that. Apparently one of the signs of hypothermia is being confused however most likely if you are confused that will be because you are trying to work exactly how in the year 2023 our leaders decided to literally put cars (which we need least) ahead of bikes (which we need most).

If it is a car not moving with its engine on: if your City like mine theoretically opposes idling (but in fact does nothing about it), you could ask the person to turn their engine off, but why would you do the City's job for them (and most likely get cussed at in the process)? Instead do what I do: stand patiently in the howling wind and rain waiting (or sunshine) for that person to switch off their tragic forsaken f*cking heap of absolute dog shit, and then be on your way. FYI there is about enough petrol in the average crap wagon to keep it idling for about 36 hours.

While you are waiting you could do sums in your head or imagine what it is like at the edge of the Universe or eat a snack.