will i get ban for spam laughing

There was a guy like 2 years ago or so that found a way to bind his taunt to literally every key in the game. He ended up taunting in excess of 1000 times per game. He was warned to stop and didn't and was eventually permabanned for it. So I mean it's not completely impossible but you'd have to push it really really far.

Is that all you're doing? Are you standing in your fountain spamming laugh all game? Probably looked down upon in most cases...

No, but I kind of wish you would. But to be on the safe side, I would suggest not doing it again.

No you cannot be punished for using any built in taunts like mastery spam or laughing. There is nothing wrong with laughing the entire time you're in lane. Mentally baiting your enemy laner into diving you is a solid tactic and works really well with champs like ezreal (you belong in a museum) or some of nunus taunts and especially well with the blitzcrank laugh XD

Happy laning!

nope just muted usually.

Well, pretty much anything you do with the intention of pissing off people is bannable. But your intention is kinda hard to prove. What's easier to prove is whether you are willingly pissing off people, which would be the case when people ask you to stop and you refuse. That's especially the case when it's your teammates that ask you to stop, since you are then forcing them to mute you, which harms team communication.

I'm not a Rioter, but I do believe you should be fine as long as you don't continue after being asked to stop.