My son was not allowed to board the plane in the US to travel to Thailand as his round-trip ticket was for 31 days--he did not have a visa. While he was waiting by check-in, my husband bought him a cheap ticket to Viet Nam which did the trick allowing him to board.
OK, thanks for all the input. I was asking for a friend's son who is in the middle of college finals and flying here directly after. This involves doing an expedited passport and rescheduling some finals (not easy this late in the game, but possible). Looks like it is necessary though.