When someone is tailgating me I slow down. No brakes, just foot off the accelerator.
Because, firstly, I'm an arsehole, and secondly its the only remaining control I've got to make the situation safe again by giving myself enough space behind me for the speed I'm doing. Of course those few mindless idiots who realise what I'm doing and back off, I'll return to my original speed.
Generally they had the shits with me in the first place for doing such horrible things as following the speed limit, which I do as I pretty much have to the way speed limits are enforced here in .au if you actually get caught