Chandler: (sighs and gestures to explain) There's a beautiful woman at eight, nine, ten o'clock!
Ross: Oh. Hello!
Chandler: Oh, she's amazing! She makes the women that I dream about look like short, fat, bald men!
Monica: Go over to her! She's not with anyone.
Chandler: Oh, yeah, right. And what would my opening line be? 'Excuse me. Blarrglarrghh.'
Phoebe: Oh, oh, but you know, you always see these really beautiful women with these really nothing guys, you could be one of those guys.
Monica: You could do that!
Chandler: You think?
All: Yeah! Absolutely.
Chandler: Oh God, I can't believe I'm even considering this... I'm very very aware of my tongue .
Ross: Come on! Come on!
Chandler: Here goes. (He walks over to her but just stands there.)
Ross：Stand back everyone, incoming ego shrapnel.
Chandler: All right, I can do this. (Walks over and stares at Aurora)
"Here goes" is a slang way to basically say "I'm going to try this now!". It normally has an underlying implication that the person saying it does not know whether or not their actions will be successful. So in this case, he isn't sure if he will be successful speaking to the woman he is attracted.
"Incoming ego shrapnel" - this is a euphemism. In this case, it means that Ross thinks Chandler will be unsuccessful, and that his ego will be negatively impacted in a way that requires his friends to console him. "Shrapnel" is a term that refers to bits of metal or other debris that randomly cause widespread damage in the local area after an explosion.
I'm very very aware of my tongue = I'm apprehensive about what I'm going to say
This is not a common saying, by the way.
sorry, I kinda failed to get "I'm aware of my tongue" and forgot to put it in red. Could you guys explan it to me with some examples?
so here goes isn't equal ot here we go, is it
Oliver has explained those 2 phrases well! :) I'd like to add on to his explanation of "incoming ego shrapnel". Ross says that because he thinks that the girl might burst/blow Chandler's ego, which means to destroy Chandler's confidence. So he is joking that it might be like a balloon that bursts or a bomb that blows off and scatters shrapnel everywhere.