If you want someone to be addressed in the second person when you're roleplaying, DO NOT EMOTE IT. Pose it, and take advantage of PROPER pronoun replacements. As well as verb parsing.
If you want or need to use emote, spell the character's name out. Third persons won't be confused this way, whether you know they're observing or not.
Consider a situation like this - a player THINKS she's alone with another character and does the following:
:gives you the finger.
Uhh, who? You can't know who might see this, besides the one character you intend to address.
The character they're trying to roleplay with begins keying in their reaction, but meanwhile, a hidden third character believes they're the one being addressed (we can't tell poses from emotes on the receiving end, you see) and they react to being discovered!
Formerly hidden unintentionally-addressed player does the following:
What do you know... they don't have a clone and have been removed from the game permanently because they tried to get cute with the roleplaying tools.
If pose is too hard and you don't feel like you can use it, spell the intended character target out in your emote:
:gives Jambalaya the finger.
Spelling "you" in an emote is wrong. Use emote properly or learn to pose. No character is going to feel like YOU are doing it wrong if you address an emote to <charactername> instead of to "you". On the other hand, spelling "you" can have unintended consequences and can ruin roleplay. You can't know who's watching or who's present.
This was overdramatized and no players were harmed in the production of this public service announcement, but, Sindome provides tools which really do need to be used a certain way. If you come from another M** where addressing actions in the second-person voice is what you do, learn not to do it here.
Emote: address people in 3rd person, spell their name.
Pose: Do the same, but enjoy automatic pronoun substitution and verb conjugation. THIS is how the target will get to see "you" when they read your action onscreen.