Relating to Xerxes son of Darius, both of them anciet Persian emperors.
Described by Herodotus, Xerxes himself was exactly as a tyrannical and nutty as an all powerful god-king ought to be and was prone to insane, disproportionate punishments and temper tantrums which included whipping the Hellespont for not obeying him.
Therefore the act of Xerxesing describes actions that are cruel, mad and over the top, usually performed in a fit of rage. Getting Xerxesed is far worse than usual punishment and is to be avoided at all costs.
'Oh god, did you see what happened? She absolutely Xerxesed him...I don't think he will ever be able to look at a baguette the same way again...'
The use of others to create warmth with mere body heat. Similar to a penguin huddle. Multiwarming can be achieved with a minimum of 2 participants (presuming they are effective heaters) and no maximum number.
'Captain Scott, I am going out and I may be some time.'
'No! Wait! We may live yet, if we multiwarm!'
'I'm sorry Captain, but I just don't feel comfortable with that.'