Casey Affleck Joined Ben and Lindsay Shookus on Comedy Club Date, Source Says

Todd Williamson/Getty Images for Amazon

Ben Affleck and Lindsay Shookus'
latest outing was a family affair. 

The couple was joined by Ben's brother, Casey, on their date at Hollywood comedy club iO West on Wednesday night, a source tells ET.

WATCH: Ben Affleck Has Another Dinner Date With Lindsay Shookus After His Mom Hangs Out With Jennifer Garner

According to ET's source, Casey "seemed really happy and easygoing" as he snuck into the club after Ben and Shookus arrived, taking a seat next to his brother halfway back on the iconic club's main floor. Ben was also seated next to Shookus, who was a "guest of honor" at the club as she scouted talent during their annual SNL character comedy showcase (the Saturday Night Live producer attended the event last year with Jon Hamm, whom she was also rumored to have dated).

About 15 comedians took the stage on Wednesday night for a 90-minute show, and while Ben and Shookus were seen chatting during the show, an eyewitness says it was "more of a work event for her than a date night," as she had her assistants there with her.

"Ben and Lindsay were incredibly nice to everyone, and having Ben there made it an even bigger night for all the comedians," ET's source says, adding that though the couple tried to avoid paparazzi by entering the venue separately and leaving through a back entrance, "They were really nice to all the staff." Shookus and Ben, who recently completed rehab for alcohol addiction, were not seen drinking.

RELATED: Jennifer Garner Runs Errands With Ben Affleck's Mom -- See the Sweet Pic!

After their comedy club outing, the pair enjoyed dinner at Mario Batali's restaurant, Pizzeria Mozza, in Los Angeles. See more in the video below. 

Reporting by Lauren Zima.