collar tug 

Somebody does this when they are in an awkward situation, feel guilt or are under pressure. They also make a strange noise and tug on their collar to indicate that they are uncomfortable. This often happens in "The Simpsons"

Homer did the collar tug when he was giving a speech and everyone booed

collar tug by collartugger October 31, 2011

180 collar tug 

when you're in a heated situation , (or nervous)

using your finger to pull the collar of your shirt

"hey isnt that you're mistress?" umm no,what arey ou talking about.... (now is the time to preform a 180 collar tug)

180 collar tug by jurduan September 21, 2013