Lindsay Lohan and Lily Allen became fast friends after being introduced by DJ Mark Ronson. (Mark is the brother of Samantha Ronson, the longtime girlfriend to Lindsay.)

While Lily was in Los Angeles to promote her new album, It’s Not Me, It’s You, she and Lindsay enjoyed a night out together, which ended at Shamrock Tattoos in West Hollywood.

Lily and Lindsay hung out together at Chateau Marmont on Wednesday night, but they weren’t done for the night when they left the bar. Instead of heading home, they went to the tattoo parlor.

Both girls showed off their ink in their own way. Lily posted a photo on her Twitter account, while Lindsay flashed her new artwork for the photographers during a shopping trip yesterday.

Unfortunately for both girls, the Shhh tattoo is not exactly original. Popstar Rihanna has the same marking on the same index finger, and she had it first, having been photographed with the tattoo as early as June 2008.

Perhaps Lindsay and Lily were making a show of solidarity with Rihanna after the domestic assault events that happened right before the Grammys. The Shhh tattoo is Lindsay’s fifth. She also has a star on her wrist, a heart on her hand, the word “breathe” on her wrist, and the phrase “la bella vita” on her lower back.