The most I'd do is smile. I can't laugh at something that isn't funny to me.

Depends on the person. If I'm not concerned about hurting their feelings I won't laugh, and usually that's easy with close friends.

My laugh quietly and easily. Unless it's like a bad bad joke as in shitty then I'm not gonna laugh to be polite.

Yes

I say w o t

i laugh cos i find it funny how unfunny the joke is

I break down and try to survive the pain.

I don't remember ever being in that situation, not when it's just me and them so that they'd notice if I don't laugh. When with a group of people if someone tells a bad joke (and I find a lot of jokes that other people find funny lame), I don't laugh. I'm not sure what I would do if it were just me and them.

If its a joke does no harm

Yes, out of politeness I try to laugh. Or once when I was REALLY high this corny guy at work had me in tears. Edibles are like a performance enhancer for laughing at things.

Nah, I will probably do the 'womp womp' sad trumbone sound

https://youtu.be/CQeezCdF4mk

Honestly I normally have a dead pan reaction - makes the joker feel like shite haha (although thats not really my intension).