When Im a player, I usually say "I step forward and attack", but usually it is sort of out character because I say things like (pointing to square on map) "I go here, I attack the goblin, and I roll a 3"
So im sort of in character... sort of... everyone else just says "Foobo the Red Steps uses his lightning spell" and then rolls, saying "i got a (whatever)"
The group isnt really into the whole "acting" thing, and since we are all in High School, most of what we do is just hack and slash. Very little roleplaying involved, unless its to the DMs advantage.
DM "Im sorry, but i cant allow your palidin to save the rest of the *evil* party. Its against his alignment."
Player: "fine! ill change my alignment and do it anyway"
DM: "but you will lose all your nifty spells and abilities..."
Player: "Nevermind. I'll just let you evil party members die. Sorry."
Other Players: "What!!!" *grab traitor, give him a noogie*
DM: "MWMMWMWMAHAHAHAHAHAHAHAH"