uncontrollable laughing

[mjandrews96]

what is the condition or syndrome called when a person cannot make a remark, have a conversation, ask questions without constantly breaking into a laugh without them knowing it or being unable to stop themselves doing it... i know a couple of people who do this, one is far worse than the other

[Scarlett]

I don't know of a syndrome, but it does sound like they are very nervous people, who are trying to make the other person like them, by constantly being jolly or jokey.

[Quizmonster]

There is a condition known by the French name 'fou rire', which means 'mad laugh'. I'm not certain it applies exactly to the situation you describe, but an extreme example of the kind of thing it does apply to is, say, getting a fit of giggles at the graveside during a burial. 

[Ouisch]

Sometimes uncontrollable, inappropriate laughter is a symptom of Tourette's Syndrome.

[chickiechick]

it is possibly tourette's syndrome? - people have different symptoms.  The more they think about something the more they have a huge urge to do it/say it.  One very serious symptom of tourette's is when people swear at people they don't even know but it's because the more they think about not doing it the more they have to.  A friend of mine has bad twitching with his tourette's which means he is contantly doing weird shrugs/twitches/strange facial expressions to himself.