Onyxia's from Blizzard's Warcraft, Luffy (inside her belly) is from Toei's One Piece and this screenshot's taken from Valve's Garry's Mod.

She just swallowed the future King of the Pirates, himself, in his Gear 5 form, just like Kaido did, but the situation just ended up with him blowing up her belly into the size of a blimp. Onyxia then said "Fool! Do you think you can stop me with such a pathetic strategy?" then he answered from the inside with an echo "You got that right, miss!" and she is like "...Curses." Obviously, Kaido may not be able to warn any other dragons, due to him being defeated in the first place.