The Avengers star Jeremy Renner once experienced a strange flight from Los Angeles to London when he accidentally took a Viagra pill instead of a sleeping aid.

Determined to catch up with his sleep on the 11-hour journey, the movie star popped what he thought was an Ambien only to realize minutes later he had mixed up his 'A' with a 'V' - and instead of sleeping he spent the flight wide awake, with a painful erection.

Renner explains, "I had to get off the plane to go to work so I had to sleep on the plane... Somebody gave me some pills... so great.

"I took a little sleeping pill... and I realized nothing's happening but something else is happening, and I realized pretty quickly that that 'A' was a little 'V' on the pill.

"Not only did I not sleep on the entire flight, I was camping... There was no walking. If I had to go to the restroom, it was so embarrassing.

"I had Dennis Hopper, God rest his soul, laying next to me and his daughter was there playing with this little glass menagerie on the ledge... I'm like playing with her and I'm like, 'Hold on a second, man. I'm gonna go to jail, I'm gonna get arrested. This does not look good.'"