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.'