143 means "I Love You."
One letter in I,
Four in Love,
and three in You.
Musiq made a song about it.
See sometimes words may get in the way
Of things that you really really mean to say
So I wanna out this time to make sure that how I really feel
Gets through to you
Cause listen
There aren’t many more ways and words that I can say
So I choose to tell you how I feel in a numerical way
Got so tired of trying to find the most complicated way
To say it to you so I simplified and broke it down
To 143 – and that means I love you
from:
http://www.urbandictionary.com/define.php?term=143