If somebody is tailgating you, you have no idea why they are doing so. They may just be impatient, or you may be driving well below the normal traffic flow, or they may even be trying to get to a hospital or other emergency.
Whatever the reason, you can either ignore them, or move out of their way when it is safe to do so. If you are really concerned about their driving, then move over (when safe), make a note of their registration number and report them to the police.
Taking vigilante action (whether it's braking hard, speeding up and slowing down, spraying them with windscreen wash or whatever) is stupid, childish and potentially dangerous - and is frankly the behaviour I might expect from drivers of Saxos and Novas with stupidly large exhausts, rather than Lexus drivers.