You want to tip your waiter/waitress in a bar, but have no cash, and the card machine doesn’t offer the “Do you wish to add a gratuity?” option.
You want to be able to provide a tip from your Monzo card with only the items available at the dinner table.
In your Monzo app, create a “Tip Code” of a user-defined amount (e.g. £5) which uses a randomly generated series of letters and numbers (short enough to write down quickly on the back of a receipt) which another Monzo user (in this case the waiter/waitress) can enter into their Monzo app to receive the tip.
This code could be time limited (say seven days) to avoid wasting the money if it’s not claimed, while also giving the recipient time to sign up to Monzo.
Apologies if this is an often suggested idea, I couldn’t find anything via search.