'Unfortunately I got stuck on the Earth for rather longer than I indended', 
said Ford. 'I came for a week and got stuck for fifteen years.'

'But how did you get there in the first place then?'

'Easy, I got a lift with a teaser.'

'A teaser?'

'Yeah.'

'Er, what is...'

'A teaser? Teasers are usually rich kids with nothing to do. They cruise around
looking for planets which haven't made interstellar contact yet and buzz them.'

'Buzz them?' Arthur began to feel that Ford was enjoying making life difficult 
for him.

'Yeah,' said Ford, 'they buzz them. They find some isolated spot with very few 
people around, then land right by some poor unsuspecting soul whom no one's ever 
going to believe and them strut up and down in front of him wearing silly antennae 
on their head and making beep beep noises. Rather childish really.'

From the book "Hitch-hiker's guide to Galaxy" by Douglas Adams