Steven Tyler shocked shoppers at a US hardware store by serenading them with two of Aerosmith's biggest hits last weekend.

The Rock Star - who checked into rehab in December - launched into a cappella versions of 'Dude Looks Like a Lady' and 'I Don't Want to Miss a Thing' over the loudspeaker system at a Californian Home Depot store this weekend, shocking staff and shoppers.

A source told website TMZ: "Steven also swallowed a few mouthfuls of gas from a helium machine, for blowing up balloons, and kept singing in a high pitched Bee Gees style. He was very relaxed though, and happily signed autographs for anyone who asked."

The troubled star is currently on hiatus from Aerosmith after a Rocky few months with the group. He entered rehab last month to seek treatment for an addiction to painkillers, which comes from years of orthopaedic injuries.

The other members of the group have said they are looking for a replacement, but have no idea if it will be on a permanent basis or not.

Guitarist Joe Perry said: "We're going find somebody to get in there and fill that spot. We'll play Aerosmith songs. Maybe we'll do five shows, maybe we'll do 20 shows, I don't know. And hopefully sometime Steven will come back."

Steven's impromptu performance was not the first time he has exercised his vocal chords in public recently.

Earlier this month, he reportedly turned up at a karaoke bar in Palm Springs, California, where he joined locals in a rendition of 'I Don't Want to Miss a Thing'.

Mike 'DJ Kermie' May, who hosted the event, said: "All of a sudden, near the end of the song, Steven grabbed the mic and started singing. The whole bar surrounded him and he just started singing the whole thing. Karaoke will never get better than that."