I have recently started a campaign for four players who were interested in D&D. This being my first time being a DM/GM, I decided to go ahead and run the Mines of Phandelver module. 

One of the members of the group, a Druid, who in my opinion is really only here because the other three were interested is the one I'm having trouble with. Whenever RP takes place he seems to be unable to control himself and laughs. It is having a negative affect on the group, as all the players tend to narrate out what they say instead of say what they want to say. I know this is a common occurrence for new players to RPGs. However, when they narrate out what they say I'll instead encourage them to say what they want to say. 

Yet the Druid will always laugh, I feel that the players are more unwilling to talk in character because of this. The Druid even straight up doesn't talk to NPCs because he continuously brings up his Personality Trait (IIRC) which states that his character is "Awkward in social situations". 

As well as a DM, when I role-played a Nothic I attempted to make the Nothic sound evil with maniacal laughter. The Druid just blew up in laughter, I could not personally do a good job after that, feeling the pressure from the group. Instead I headed the Nothic into combat rather than continuing down the path of a possible non-violent resolution with the PCs. 

I talked to the member, but he continues to laugh. I am hoping to resolve this situation without totally ruining the RP experience for both himself and the other players in the group.