What is 103?
1.
Said when two people say the same sentence simultaneously.
If then one says 103 and the other cannot speak until someone calls him/her by name.
At least that's how it's used in Hungarian.
A: That guy is handsome.
B: Aww how cute!
A: 103!
B: ...
See
2.
to bust on a sandcastle
originated from the native americans
a form of entertainment if the sandcastle falls you automatically win
I 103d on that shit at the beach the other day