I've always been a little leery of whispering in my games while playing them (in Team League play). Generally speaking, there can be three to several people observing your game. But what if your opponent is also logged in as a guest and sees all the whispers that are being made during the game - especially the whispers you're making?
This screen-grab is from a game of one of our team members. When I first started observing the game, it was just me, TeamLeague and that guest observing that game.