When Mutt Williams and Indiana Jones talked in Arnie's Diner in 1957, Mutt took out his comb, dipped it into Joe College's drink at a nearby table and started combing his hair. Joe's girlfriend noticed and pointed it out to the other people at their table. They looked over to Williams, but when he showed no reaction they turned back to their conversation and the matter was left there.
In the jungle camp at Brazil, when Jones showed his reluctance to co-operate with the Soviets, Irina Spalko drew her rapier and pointed it at Mutt's throat. Mutt stammered "Whoa! Stop! Wait!", took out his comb and started combing his hair. He then said "I'm ready.", and continued to Jones "Don't tell these pigs a word."
Behind the scenes
The comb, together with the switchblade, was one of the two props specially designed for Mutt Williams. During production on Indiana Jones and the Kingdom of the Crystal Skull, George Lucas drew a comb from his pocket that he had used for the last fifteen years and showed it to Doug Harlocker, the film's property master, as a reference. He also gave Shia LaBeouf special lessons in comb etiquette. 
Notes and references
- Mutt's comb prop replica at www.yourprops.com