From time to time I manage to piss off some script kiddie wanna-be hacker and they decide to "teach me a lesson" by DDoSing my personal web site. I watch them in amusement and take no action. It's always interesting to see how long it takes them to realize that they made a mistake in assuming that I care about my educational resources that I offer for free being temporarily unavailable.
Some years ago, there used to be an irc channel where you could post an IP and some random botnet would DDoS it. I sometimes watched my fail2ban logs and alike and just fed the most popular IP into that channel. I wonder how many days I may have ruined. xD