Scott A.

It means to eat out a women’s vagina while fingering another woman in a threesome.

It originated from a boy in QLD, Australia who showed to his ability to eat out a woman and fingering another at the same time on video so it became a saying. It is now a celebrated move all throughout Australia.

Scott started fingering Hannah and eat out Rachel on a livestream.
He became a saying for when you do those actions since then.
Example: I did a Scott A. On the German twins!