Pregames often are single sex, with men playing beer pong or video games, and women drinking vodka sodas or a peach-flavored Champagne called André and refusing to head out until they have captured the perfect photo, which they promptly post to Instagram and Facebook.

“You could have this really amazing night, but if you didn’t get a picture, it’s like it didn’t happen,” said Ms. Parr, 22, a senior at Gettysburg, whose friends often order designer outfits from the Rent the Runway Web site because incessant documenting makes wearing anything more than twice taboo. “It’s crazy how much pictures consume our lives. Everyone knows how to pose and how to hold your arm and which way is most flattering, and everyone wants the picture taken with their phone.”

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Leave your phone at home or in vehicle if you are hanging out with friends; it'll make a world of difference.