Here is the rule: beg a resign if you want but you MUSTN'T use words, gestures or anything. You must make your request using legit chess moves exclusively. Capture queen, lots of pieces. Push passed pawns to their goal. Drag his weakened king out of safety. Exert unbearable pressure. Etc etc.
PS: If for any reason you cannot do any of the above, why the **** do you feel entitled to have the other guy resign? Please explain.
Occasionally, I play a friend OTB. Often they are infrequent chess players. I do not like to play anyone without a clock. But it is hopeless. These kinds of players are offended by the suggestion of using a clock and feel pressured.
OK...whatever. Then they take 5 minutes to make the first move. Maybe 10 on the second. They need to use the restroom. They go when it is their turn, so I have to swallow spit for 15 minutes until they return. Then they take 20 more minutes to move.
I just "suck it up". What else can you do? These are "friendly" games. I would never ask them to resign...not even when they are taking 30 minutes to move and they are in zugzwang and my next move is checkmate.
However, there is one thing I do do. Say they have already taken 10 or 15 minutes to consider their move. I will look about the room, then look them in the eye (well, they are usually looking down, staring at the board and pieces), with an expression of combined innocence and confusion and say: "Have you moved yet?"
But that's as far as I will go. To do more, as suggested above, is to be a douche.
I think my patience has come with age. I am an old man. Waiting for the wife and daughters has been excellent training in patience and "biting the tongue". To do otherwise invites "unintended consequences"...namely catastrophe. So, young men..."listen up"!