Divide the group into 2 or 3 teams. In between rounds the host should ask for a volunteer from each team. Volunteers should be different each time. The host should mention the category for that round but should not mention the activity. For example, the host might say "For this round I need volunteers for 'longest'". Once the volunteers are identified you can proceed to the activity. The sample activities are listed below. Have fun and make up your own.
Longest - tongue
Widest - spread your feet
Shortest - time saying the alphabet
Longest - time holding your breath
Most - number of buttons
Highest - raising of eyebrows
Weirdest - face made
Biggest - smile
You can keep score and give each team a point for the winner of each round.