The year the radio station company where he worked held its holiday party at a dive bar, Ryan Arnold walked in and saw coworkers passing around a tall glass boot filled with beer. He heard the office manager belting out '80s power ballads between whiskey shots. Arnold's first thought was, "When can I leave?"

More than 20 years later, he still remembers that awkward social event he felt obligated to attend. Arnold, 46, who describes himself as socially anxious, now thinks twice before accepting invitations to group gatherings.