No matter it’s truth or not, laugh can really ease our stress and make we feel better.
However, there’s the condition, where you shouldn’t laugh in these circumstances:
When you’re feeding your child with food, you shouldn’t do it. As the food inside your child’s mouth might lead to unexpected incidents, such as suffocate or brain hemorrhage.
People after surgery are not allowed to laugh too much, as it slow down the wound healing process!
Those Hernia patients are not encouraged to laugh loudly, as the laughing might accelerate the hernia and leads to intestinal necrosis!
Aside of the above three matters; you can laugh whenever you want.
Note: Laughter face's credit goes to Sodahead.