Hi. We are a group of 9 guys who are going out in Paris, and wants to go to a popular and a fun place to eat in august. But wander which place to choose?
SillyA, I will admit that I've only been to Paris a couple times, and never with a group of 9 guys, but I have just a couple hints to help you narrow your search. I'd recommend picking a neighborhood to start, perhaps Les Marais since I've walked through a couple times and it seems pretty hip.
I'd be sure to check out reviews of places that catch your eye, with a particular note for whether or not the establishment will take reservations. A group that large will likely need them, or at least an accommodating host and servers that know to expect a big party (even if they can't reserve a table for you).
Sorry this doesn't answer your question specifically, but I hope it helps!
You're talking about the evening, I suppose. If so, I suggest going to Place de la République where it will probably be too early to get a meal (depending on when you are starting) but there will be lots of places where you can get a drink. From there you should walk up the rue du Faubourg du Temple to the Canal Saint Martin, which pops out of its underground tunnel just to the left. (Anybody hungry will have found some excellent doner kebabs on the Faubourg du Temple already.) Walk up the Canal Saint Martin -- either side is fine and there are lots of bridges to cross over back and forth at whim. If you are young, by then you will regret not having bought all of the supplies for a picnic with lots of drinks, because you will see huge crowds of people all along the canal imbibing and gobbling junk food if necessary. Last time I was there (last week) there were even people jumping into the canal to swim to the other side.
Walk up the canal as far as you want. Just before Stalingrad on the left there is the excellent Point Ephémère alternative music venue spilling out onto the banks of the canal. It gets wilder as the evening progresses.
Back up at Place de la Bataille de Stalingrad (even though we all just say 'Stalingrad' obviously), there is the very impressive and historic building housing the Rotonde de Stalingrad. It is a very good and reasonably priced restaurant in an astounding setting. Service is very bad but only if you are in a hurry. Basically you just wonder if your waiter has quit and gone home while you wait for the food.
If you prefer more drinks, there is a great upper terrace on the right facing the Bassin de la Villette. It has happy hour until 20:00 but helpfully informs you with a sign that happy hour at the place facing them has happy hour until 21:00.
Not satisfied yet? Keep walking up the Bassin de la Villette and you will find multiple bars and restaurants on both sides, sometimes on floating barges...
I could go on, but I hope you have the picture by now. If lacking imagination, by the time you reach the Pont de Crimée at rue de Crimée, you will be at the Saint Christopher's Inn and the location of one of its famous and wildly popular Belushi's Bar.

Been there, done that regarding McD😃 not looking for special cuisine, but a good times with good friends in Paris. And we for to eat, why not a fun And cool place in a cool city?