Can you guys please explain your guesses? These one-worded responses are starting to get spammy, especially with whimsyboy's apparently nonsensical "Something." response.
Death? Someone that is close to you dieing will make you cry. If you hate them it can make you laugh. You can see them dead but you cannot see death itself.
Farting? If you fart it can make you laugh. The noxious smell can make you cry. You can't see it. You might be able to see the skid marks in your pants but not the fart. LOL