Before Orton had the opportunity to follow through on a planned heel turn, he wound up injured in his first match on Raw after jumping brands. Whilst that shouldn't be a CMOA, it lead to Orton giving weekly news updates on the status of his injury as if it was the most pressing story in the WWE.
During his match with Mick Foley at Backlash, Randy Orton proved to be pretty hardcore when he let Mick drop him into a pile of thumbtacks. The look on Orton's face when it happened tells it all. If you didn't think Randy Orton was badass after that, nothing will ever change your mind.
As Scott Keith pointed out, even Triple H wasn't crazy enough to do that spot during his 2000 feud with Foley, a feud that might have spilled more blood than any other in company history.
SummerSlam 2004, when Orton pinned Chris Benoitclean to become the youngest World Heavyweight Champion in WWE history, after Orton's mentor Triple H had spent months failing to beat Benoit whilst cheating.
Later on, Orton was told by Triple H to give him the belt or face the consequences. While seeming obedient at first, Orton spat in Triple H's face and officially broke away from Evolution, effectively becoming a face and racking up another CMOA for himself.
Suckering Eric Bischoff into calling himself a legend, who only realised just what he'd done when he noticed the grin on Orton's face. Cue RKO.
Whenever he gives the RKO to someone in midair.
Or from the top rope.
More recently (7/12/10 edition of Raw, to be exact), Randy's RKO on Evan Bourne while Bourne was in the middle of a Shooting Star Press. And Orton wasn't even standing. He went from laying on his back to a midair RKO. He's that awesome, apparently.
He already counter the Attitude Adjustment into an RKO but on 9/13/10 he did it through a table.
Or what about this gem to Rey Mysterio? While Rey's on the apron and the ref is distracted with trying to grab Finlay'sshillelagh... *snicker*, Randy Orton slides into the ring while Rey's trying to springboard, times the RKO perfectly with Rey's leap, slides out of the ring, and is already walking nonchalantly back up the ramp by the time the ref turns around.
On the 12/6/10 edition of RAW, Randy Orton delivering an RKO to Michael Cole.
And the next week, he powerbombed "former WCW champion" David Arquette right through a table.
On the 2/7/11 edition of Raw, The New Nexus attacks him, the first he does is beam David Otunga in the head with the mic and later CM Punk taunts him and get his nose busted for his troubles.
While the outcomes were fairly controversial, his matches with Christian for the WHC are possible Match Of The Year contenders.
At Hell In A Cell 2011, after losing to Mark Henry, Mark tries to put him in the "Hall of Pain" (Mark wraps a steel chair around an unconscious victim's leg and hits it with a second-rope splash). At the last second, Orton revives and dodges the splash, then goes postal on Mark with the chair.
On the 10/14/11 edition of Smackdown, he won a battle royale by last hitting The Miz with an RKO while both are on the apron. They both fall out, but Miz hits the ground first.
On the 12/9/11 edition of Smackdown, he must defeat Dolph Ziggler in seven minutes, fifty three seconds. Despite Wade Barrett's interference, Randy pins Dolph with an RKO with two seconds to spare. Barrett angrily assaults Orton after the match and tries to send him through a table, but Orton fights him off, then powerbombs Ziggler through the table.
At Tables Ladders and Chairs 2011, Wade Barrett positions a groggy Orton onto a table, climbs to the top rope, and goes for a diving splash. Orton pops up and gives him an RKO in midair, sending Barrett through the table.