Stand at the supermarket checkout, gazing vaguely into the distance, and only when told the total say ‘Oh!’ and start looking for their handbag.
When you have explained that you are too busy just now to answer their e-mail properly, at once send you two more.
Say ‘I must go now’, then stand in the doorway talking for the next ten minutes.
Stand in doorways in general, or other narrow places, making no attempt to move until one has to ask them.
While visiting, take the opportunity of one’s temporary absence from the room to ‘tidy’ the papers on the desk, or lift the lids of saucepans and change the heat under them, or read the labels on one’s medicine packets, etc. etc…
In general, insist on ‘helping’ one when one has not asked for help.
I could go on for pages, but have already said more than enough to cancel the recent increase in readership.