What if I tell you I can listen to comedy on the train because I love cackling like a madman in a crowd full of strangers?
Kidding again are you? What made you laugh out loud?
I can't remember why I did it, probably I saw something funny on my phone
It is okay to find things funny but you should be careful about laughing too loud and causing a disturbance. People don't like to hear loud noises when they are in transit to somewhere.
Why? Do you think it's noise pollution?
Loud noises such as that can startle people, and make them scared. They might see you as careless and immature and give you dirty looks, not to mention shake their head and fists at you. Do you really want that attention on yourself?