It's peals of laughter - meaning loud or ringing.
It is something that you do when you are happy and you let out giggles, laughs, or possibly a fart or two...
Laughter attracts joy, releases negativity, and a lead to amazing cures :)
Funny stuff obviously makes you laugh, nervous situations sometimes make you laugh nervously, or you could force a laugh to pretend you find an unfunny joke funny.
No, Infact laughter is really good for you it help's you burn calories and is good for your heart and you.