Quote Originally Posted by Wowik
Lingvo dictionary article:
http://lingvo.yandex.ru/en?text=%F1%F2% ... B%F8%EA%EE

Трезв как стеклышко - antonym - Пьяный в дым.

When somebody drinks too much, he always sees everything in a fog (дым).
When somebody has not been drinking at all. He sees everything as through a crystal (стекло).
That's funny!