Now, I could go into a huge, long rant about how idols are people too and we need to respect their privacy by not stalking them or putting pressure on them to be prefect, you know personal life stuff. However, I wanted to focus mostly on stage incidents that occurred this year.
It’s common sense to most people, but some don’t realize that you can’t throw things at idol stars.
1. Don’t throw things at people in general.
2. They’re performing. They will not have time to react to/catch what is being thrown.
3. You could injure them.
There are more reasons, but I’m going to assume you’re mature enough to realize that throwing things at people is not a good idea.
There have been some other incidents this year as well. For example, someone ran on stage and attempted to kick Wheesung, and in the same week Girls’ Generation’s (SNSD) Taeyeon was almost pulled off stage by a man.
Here’s videos of some of the incidents that occurred this year.
Yesung gets hit in the eye by a chilli pepper during Super Junior’s Super Show 3 in Singapore.  (Incident occurs at 0:29)
Heechul gets hit in the face by a placard during Super Junior’s Super Show 3 in Shanghai, causing him to receive a cut just below his eye.  (Incident occurs around 0:06)
On the show “Night By Night” Bigbang’s Seungri once revealed that TOP had had sunflower seeds thrown at him by a fan. The fan yelled, “Always remember me!” Then threw a handful of the seeds at TOP. Even if he does remember that fan, he’s not going to have any positive memories associated with her, or want to be her friend after that, so what’s the point? Later, TOP asked the fan why she threw them and the fan said that once she’d seen a story about a fan slapping Kang Dong Won during a fan signing and that he’d remembered that fan, so she wanted to be remember too. TOP asked her not to do it again, but other fans found out and also began throwing presents and asking to be remembered.  Idol stars are human too. Think about it. If some random person slaps you, you’ll probably remember it, but if you ever see that person again would you want to talk to them, or get to know them? No. They’ll just be that rude person you don’t even know. I’d rather not be remembered at all than be remembered as that rude fan who threw something at my favorite idol star. I know some fans may be a bit young, but even so, we should all be mature and realize that idols need to be treated with respect.
Singer Wheesung got attacked by someone, though I’m assuming he wasn’t a fan, it’s still a good example of disrespect.
“On April 19th, a representative from Wheesung’s agency made a statement, “At the time, a man went up to the stage and attacked Wheesung. He considered it as just a minor incident and responded to it calmly and completed his performance.”
The representative continued angrily, “Thankfully, Wheesung was not injured but we did not receive any words of apology from the broadcasting company in charge of the performance. It was not an informal event; it was a rather big performance hosted by a broadcasting company and we wonder why the security was so loose. All singers, not just Wheesung, are participating in minor events around the nation but their security is compromised due to this lackadaisical environment.”
While Wheesung was performing “With Me” on April 8th, the assailant calmly walked onto the stage and tried to kick the singer. Though it was obviously a jarring moment, Wheesung was able to regard the incident in a cool manner, and managed to showcase his professionalism by finishing his performance.” 
On April 17th, towards the end of SNSD’s performance of “Run Devil Run“, a male audience member jumped on stage and attempted to take Taeyeon off stage with him. The other members were confused and caught off guard, probably scared too, but Sunny reacted well and tried to stop him. Comedian Oh Jung Tae managed to stop the man long enough for security to intervene.
“A representative of SM Entertainment stated after the incident, “During the latter part of the event, there was an unexpected accident. Taeyeon, however, handled the matter bravely, and security staff prevented the situation from becoming more severe. At first, the audience and concert representatives all thought that a staff member was going on stage. After the concert, SNSD returned back to their dorms and are currently resting. We’re glad that the incident did not escalate into something more severe.”’