Tight pants, justa, and make sure he takes his painkillers - alternate paracetamol and ibuprofen.
And tell him not to do what MrBIWI did - not take the painkillers because he wanted to see how painful it really was when the anaesthetic wore off .... (twat!)
Might also be a good idea to get some arnica tablets to help with the bruising. MrBIWI's scrotum was a spectacular shade of blue/purple/yellow for about a week.
(Probably best not to tell MrJusta any of this!)