The problem with bullying and playing pranks on people is that you as the bully or prankster never know how your actions will impact your target. Granted, this was not a case of shoving a kid into his locker. Ravi and Wei carefully planned to publicly humiliate Clementi and "out" him (if he was indeed gay) before Clementi was ready to do so.
This case reminds me of Megan Meier's-- the unfortunate story of this teenage girl who committed suicide by hanging herself after being lied to by an adult cyber-bully. Meier had been emailing a "boy" who she had a crush on but later the "boy" called her a liar and a slut and told her the world would be better without her. Depressed, Meier took her own life. The truth unfolded that the "boy" was instead a female adult neighbor who pretended to be the boy because she wanted to supposedly find out what Meier was saying about her own daughter. Meier's family admitted that they do not think that the intent was for Meier to kill herself. Nonetheless, that is what resulted from the cyber-bullying.
It's hard to define a line that should not be crossed when it comes to trying to get a laugh out of someone or making them 'tick' to a point where they're just pissed off but not suicidal. The truth is that line isn't the same for everyone. Getting a rise out of someone is risky. Is making fun of someone's attire acceptable but making fun of their sexuality off-limits? What if that person who gets made fun of for the way they dress wants to be a designer? Did you just shatter their dreams?
You'll never really know exactly what your target is going through to guarantee that they won't commit suicide or cause harm to someone/something else in their moment of despair and/or rage. I'm the first to admit that I like making people laugh, and I'm willing to be the butt of the joke if you will too. But what if two people who exchange jokes do so when one of them is having an off-day? You may not be aware that a person may have experienced a bad day/week, recent life change (e.g., job loss, loss of a loved one), etc and so a joke that they should just find funny goes awry. Most sensible people would avoid bullying someone or playing a prank on someone if they knew that person was in a sensitive, fragile state. The problem is, you don't always know.
So should we never joke around, never play silly pranks like tying a rubber band to your faucet's sprayer handle so that when the next person goes to use the faucet water sprays them (see pic below)? Life would be pretty dull.
I feel horrible for the people who are pushed so far to the edge that they jump off, but I also feel regret for the people that pushed them that far and didn't mean for them to actually jump. No penalty enforced by the law can equal the weight your conscience would feel (assuming you're human).