Heads Or Tails

Two Queen's students were trying to decide what to do that evening.
'I know,' said one. 'We'll toss a coin. Heads we'll go to the downstairs bar in the Students' Union and spend our grants, tails we'll go to the upstairs bar and spend our grants.'
'What happens if it lands on the edge?' asks the other.
Then we'll just have to stay in and study.'