> I didn’t know “second base” had another meaning.

Out of curiosity, what's the other meaning? I assume the primary one has to do with baseball bases.

First Base - Kissing Second Base - petting above waist Third Base - petting below waist Home Run - sex

2nd,3rd base can vary a bit, but Home Run analogy has been around for a long time.

Not really well defined obviously, but here's some information: https://www.wikihow.com/What-Are-the-Bases-in-Dating