One for sorrow,
Two for mirth (or joy, or luck, in some versions),
Three for a wedding,
four for a birth, (or a death, in some versions),
(Three and four are sometimes for "a girl" and "a boy," respectively.)
So many options.
The old nursery rhyme goes on:
Five for silver,
Six for gold,
Seven for a secret never to be told.
Eight for a wish,
Nine for a kiss,
Ten a surprise you should be careful not to miss,
Eleven for health,
Twelve for wealth,
Thirteen, beware. It's the devil himself.
Look for the signs.