The rule is really simple...
You cannot yell or even "talk" while the ball is going over to your opponents side of the court. The rules do not distinguish between the type of outburst for simplicities sake and for continuity.
If you pop a ball up and have an "outburst" it is a hindrance.
People seem to think saying "watch out" or "short" or "heads up" somehow makes a difference between saying "AHHHHHHHHHHHHHHHHHH!" or "AVADA KEDAVRA!!!". There is no difference.
The only time you can have an "outburst" is when the ball is coming over to your side of the court. In doubles, usually this means using words like "mine", "yours", "deep", or "bounce it".
I await the day where I will have to have the talk with my mixed partner because she always says "watch out". Come playoff time I can see someone calling it on us especially on a critical point. She's a 3.5 national levels player
(shes a 4.0 "B" now) and shes a lawyer. She's like a little "pit bull" lol. She's so much fun to play with. Anyway...
"In the 1980's two men dominated--sometimes each other, most of the time everyone else."