I see the term ATF used once in a while. What does it mean?

All Time Favorite (or Favorites - if you can't choose just one! LOL)  For example, TS Daisy is an ATF of mine.

So Daisy is not an officer in the Bureau of Alcohol Tabacco and Firearms. That is good to know, I would not want to meet a lady with cuffs!! Or would I?

automatic transmission fluid

Tranny Fluid

sorry...couldn't resist.

Automatic Tranny Fluid: that's good! LOL I was thinking of All Tranny Female...or All Terrain F**k....

a toda madre  - ATM

Ha! Ha! That one never occured to me!

Yes but I do admire the way Daisy expertly handles our guns! She knows that you're so supposed to relax and breathe before pulling the trigger to fire.