My first was a Game & Watch Manhole - the original brown one, not the re-released blue 'widescreen' one
. Like others, it was either a birthday or xmas present and it got a great deal of use. Hmm, might have to go and look for one on ebay now...
For the G&W fans who are keen, Nintendo Japan released a club members only cart for the DS which has Donkey Kong, Green House and Oil Panic, and are pretty much perfect clones of the original G&Ws. You can find them on ebay. Definitely worth tracking down for reaching that nostalgic high.