Simple, often secret, way of saying I Love You over text or chat, without being too forward

I miss you.

used in web forums to denote a quote that they entirely agree with 100%. the term "you took the words right of my mouth" comes to mind.

however, because they forums disable spaming by requiring people to type at least 3 characters per post... 123 comes to mind

The first 3 numbers you learned this in kindergarten I hope you looked this up as a joke

If someone is trying to attack you you say 123 and punch them

the numerical version of "abc".
Which means, "simple"

it is often used as a term denoting the word "numbers" or referred to counting

123 is also the first thing that comes to my mind when I hear the anything related to numbers or maths.

Most Easy ass password that some kid will brag about in school