"Sienna's finding it all very funny with friends have been texting her about Brienna laughing," a source told DailyMail.com.
Over the last several months, rumors have been circulating that Brad and Sienna have been getting flirtatious. One report was as recent as last weekend at the Glastonbury music festival. The DailyMail, though, says that Sienna isn't even available and is actually dating "Foxcatcher" director Bennett Miller.
"Sienna's finding it all very funny with friends texting her about being dubbed Brienna. She's happily with Bennett and has no idea where these rumors keep coming from," the source said. "They're just not true. Brad's a great friend but nothing more. They were hanging out at the Rabbit Hole at Glastonbury but they were with a big group."
On June 26, The Sun reported that Brad and Sienna hung out in the VIP area and were spotted "holding hands and stroking each other" while hanging out with Bradley Cooper and Oasis member Noel Gallagher.
The report claimed Brad and Sienna met up at 3 am.
"Brad and Sienna couldn't keep their hands off each other, touching and stroking each other at every opportunity," the source said. "They seemed really intimate."
The source added, "They seemed keen to get away from prying eyes and made a dash for the Rabbit Hole, the festival's underground and exclusive venue, with a group of friends and were inseparable as they waited to go inside. The party was cut short and they had to leave after five minutes because the venue was closing. Bradley Cooper left and Brad and Sienna headed back arm in arm to their private Winnebego."
Sienna has previously denied that there is any romance with the actor.
Still, despite the denial and the DailyMail's report, The Sun maintains that there is a romance brewing.
"It's early days, but they are very into each other and enjoying a carefree, casual summer romance," an alleged friend of Sienna's said. "They're both absolutely determined to keep everything under wraps. Their goal is to explore things without any massive publicity. It could all fizzle out, so they're waiting to see."