5 stars to the person who added common sense.
First off, watch what keywords you use. You already used two keywords that trigger an investigation from Homeland Security. Certain keywords in email or ANY ONLINE POSTING automatically triggers these bots and an investigation from homeland security. So do not use words such as "authorities, law enforcement, drill, domestic security, cops, dirty bomb, hostage, explosion, security, breach, detection, nuclear, toxic, outbreak, contamination, sarin, anthrax, chemical burn, small pox, plague, virus, exposure or several other words like that. The more hits there are the higher the priority.
So if any of those words show up online, you trigger a thorough probing and investigation.
A hacker should already know the answer to this question. But you need at MINIMUM an anonymous proxy that does not keep records of IP addresses. You would also need some other specialized software custom written for your needs, but since you are a hacker you already know how to write and compile this code. You need a good router and software to reject pings and other attempts to track you, but you already know this.
Any smart hacker would not brag on a public website that they are violating federal laws making them a target. Especially considering all activity online contains IP, ISP, browser and OS information. But any bright hacker would be using a secured anonymous proxy that does not use IP logging along with other masking software to to keep themselves a ghost and difficult to be tracked. After all, homeland security has bots tracking any possible hacking activity and that is triggered by keywords and automatically begins tracing their IP address, ISP and account suspected illegal activity comes from.