People number their limbs 1-4, then go up to each other and ask 'are you shomer negiah?'. If they have at least one free limb they say yes. the first person says what limbs he has free (only numbers so as not to give away which limbs are which) and the second person makes an offer e.g my 1 to your 3. Those limbs are then used. If a person has used all four limbs when someone asks are you shomer negiah? they say no and wave their hands 1 inch away from the 1st peron saying 'I'm not touching you' in a high pitched voice. When everyone has become shomer negiah you have to try to link up to the corresponding limbs of the four people who you previously talked to forming 1 big tzevet knot