McVay spoke about pranking his friend during an appearance Monday on The Adam Schefter Podcast. He pulled off the prank during a dinner with Kansas City Chiefs quarterback Patrick Mahomes and Kingsbury.
"We have a mutual friend that I put his name in my phone as [NFL commissioner] Roger Goodell," McVay said. "I had this friend send me a text saying, 'I can't believe you're at dinner with Kingsbury and Mahomes. You know better than this. This is tampering. You're both losing picks.'"
McVay said he showed Kingsbury the text and he looked like he "saw a ghost." McVay then told Kingsbury he should call Cardinals general manager Steve Keim.
"He [Kingsbury] said, 'I thought I was going to lose the No. 1 overall pick,'" McVay said.
"We couldn't let it go on too long, but it was pretty good. We got him good," McVay said.
The Cardinals own the No. 1 overall pick in the 2019 NFL Draft after a 3-13 campaign in 2018. Arizona fired coach Steve Wilks after one season and hired Kingsbury in January.
McVay, 33, became the youngest coach in NFL history when he was hired by the Rams in 2017. He led the team to an 11-5 record in 2017 before posting a 13-3 mark and leading Los Angeles to the Super Bowl in 2018.
Kingsbury, 39, is the fourth-youngest coach in the league. Zac Taylor -- who worked under McVay last season as the Rams' quarterback coach -- is the second-youngest coach in the league. The 35 year old was hired by the Cincinnati Bengals this off-season.
The Cardinals and Rams match up twice annually in the NFC West.