Of cameos and camellias...

As I recall, most of his major injuries were aggravated during the shooting of cameos or item numbers... the back injury, the shoulder injury (remember his fear of losing his arms? The surgery for both injuries could have rendered his left arm useless... which is tantamount to it being cut off, IMO).

The only major one I know he obtained from his own movie was the knee injury from Koyla when he quite hyperly smashed his caps in a dance sequence. Watch the making of to see how it happened. He actually repeated that exact jump during Main Hoon Na in the Chori Chori song (this probably means he's already dabbled as a stunt director during Koyla), but they softened the blow with a pile of matresses.

Well, this article proves what a softie he is when it comes to his friends, or anybody really. Maybe he could become so busy that the solution to the problem (of whether or not he should accept future requests for special appearances) would take care of itself. But then, Shah Rukh can be the busiest man who seems to have all the time in the world... so I doubt he can fulfill that promise he's made to himself to stop doing cameos any time soon.

Source
Shah Rukh Khan has readily made cameo appearances for friends as a goodwill gesture in the past.

However, he had decided to stop doing cameos after he felt that producer Viveck Vaswani tried to take advantage of his goodwill while shooting Dulha Mil Gaya. His decision worried Makrand Deshpande as he had planned a cameo for SRK in his film, Shah Rukh Bola Khoobsurat Hai Tu.

However, Makrand is at peace now as his superstar friend has finished shooting for the film. As a bonus, Shah Rukh also allowed them to shoot in his home and in his car. Shah Rukh had refused to make cameo appearances after Viveck Vaswani's Dulha Mil Gaya, for which he was asked to shoot for about four days. But when he read the script, he realised that it would take at least 18 days to complete his portion. Thereafter, SRK made the decision about not doing cameos, but we guess there are a few exceptions for friends.

Makrand Deshpande confirmed the news, "I'd mentioned my film to him while shooting for Swades and he agreed to do it. After that, I got my script together and roped in producer Amarjeet Singh. In fact, we took the film on the floors on November 2, which is also Shah Rukh's birthday. I messaged to wish him and informed him about the status of the film. This was in 2007. After that, I started coordinating his dates and I was regularly in touch with him and his secretary Karuna. He said that he will shoot with me before leaving for the outdoor schedule of My Name Is Khan. So, a couple of days ago, he just called me over to his house with the unit and asked me what he has to do. I also made a request that I will need his car and he was extremely sweet. He said we could use whatever we wanted. We shot the sequence where he tells a flower girl, ‘Khoobsurat hai tu’ as she had had a bad day. SRK leaves and that's when she realises that it was Shah Rukh Khan and she collapses with joy. After that, her life changes."

Talking about the sequence, Makrand added, "This sequence was an integral part of my film. After the shoot, he met my whole team and Preetika (who plays the flower girl) and we had a long chat."