When GD&Seungri were guests on Strong Heart.
Seungri did parodies of his Big Bang brothers.
So these was his imitations of G-Dragon.

The first gesture/act that Seungri imitated:

Seemed embarassed for his dongsaeng lol.

For the second hand gesture, he said "GD always do this".
And you know what he did?

Yes! That's right! It's the G-BOM sign!
So it shows that even Seungri notices it too!

He encorporated the sign in the "sweet medusa" part
Maybe he didnt know how to show it since GD just randomly does the sign whenever he's rapping.

And then, GD does it cool-y. 
Compared to his reaction from Seungri's first imitation, 
He seem pretty confident and happy with this that he even sort of corrected Seungri.
See the little smile from his face?

Click HERE to watch the whole episode.

Video credits: KpopMusicx4@YouTube
GIFs by: Twiddlebug@GBOMsince2006