Sit in a circle. Ask each person to produce a clause (phrase) which could go with ‘Do you mind if I ...? Or ‘Would you mind if I …?’ eg: sit down, sing a song, sat here, closed the window etc. And ask everyone to remember what each person has said; this is apparently a memory game.
When everyone has said their clause, you stand up and choose one person. Say: “Do you mind if I (use their clause)?” If it IS their verb they answer, “Not at all.” or similar and you swap places. The person standing then continues.
If they misremember, then you’ll have to decide what the authentic response would be! “Do you mind if I sit here?” “I’m sorry, that seat’s taken” for example
If you have a small group you can extend this activity at the end by asking people to get back their own seat using the same language.