O'Reilly 1.Masturbation during phone sex, using a vibrator in your anus. 2. An O'Reilly is the act of jacking off with something up your ass while on the phone. 3. First known mutant born with the ability to stop objects in a 50 mile radius from spinning. Vin: Hey man lets get drunk and go to the top of the revolving restaurant and puke on the people below. Praks: No point man we would only puke in one place, O'Reilly is in town to go hunting with Cheney. 4. Creatures having some semblance or connection to, or may actually be The Beast Examples include: Satan, Lucifer, the Morningstar, Old Scratch, Old Nick, Prince of Darkness, Greg O'Reilly 5. A word to describe someone who is very stupid. Must only be used after someone says/does something that is unbelievably, astonishingly, incredibly stupid. I do say I prefer number 4 over the rest.