Have everyone count the number of letters in their first name.
Now ask them to find someone who has the same number of letters.
Those two are now partners.
If a person can't find someone let him/her use another name s/he is called by
(i.e., a Scout named Matthew may use the name Matt and then look for someone with 4 letters instead of 7.)
If they still can't find someone pair up with a person who has the closest number of letters.