I had a friend that did an unintentional turn ORD-LHR-BLR. At immigration, turns out he didn't bother to get a visa because he didn't think he needed one (British citizen living in the US). They put him on a flight 2 hours later back to LHR and he spent the next couple of days trying to get a visa there.

Of course I had to give him grief that it was the second time that India ran a Brit out of the country.