In reply to RDE:
Lets be honest: Repetition breeds complacency.
When you have climbed and belayed hundreds or thousands of routes, you know very well the safe ways of doing things, but...
Maybe you stand a bit further out from the base of the climb because standing right next to the wall is awkward.
Maybe you sit down to belay someone on an easy section you assume they will be absolutely fine on.
Maybe you have a little bit more rope out than you should have because your leader keeps clipping gear way above their head and your feeding out is a bit slower than their pulling up rope.
Maybe you are not holding properly onto the ropes and they jump or slip in your hand before you get control of them when the leader falls.
Even the safest climbers are guilty of one of the above every now and again or any number of other little nuances which give extra slack.
Now a load of people on this thread are of the opinion that you should be having words with your belayer and I'd agree with that.
BUT
After an accident, you will probably find that your previously lax experienced belayer is now hyperattentive because of the accident that happened.
So you will probably be safer sticking with the same belayer who has been shaken up by this happening than moving to rely more on other climbing partners who have not been shaken up recently.
Ideally the complacency should be headed off before it results in an unnecessary serious fall so I'd suggest that people should infact make sure they fall every now and again outside to ensure their partner is nice and attentive! (I certainly use falling off at easy points indoors to help my climbing partners stay attentive - git that I am).
Final proposition: Don't say "watch me", it might make you feel better but it means your belayer thinks they can relax when you are not on a "watch me" section. Keep em guessing