Johnny Galecki Teases 'Emotional' Bill Gates Cameo on 'The Big Bang Theory'

The Big Bang Theory has a massive guest star appearing on Thursday night's episodes, and one of the cast members is already teasing it will be an "emotional" event.

Microsoft co-founder and 2nd richest man in the world Bill Gates is slated to play himself in Thursday's episode. Johnny Galecki posted a photo of Gates seated with a rest of the cast on the show's set.

"I get emotional with Bill Gates tonight. Doesn't happen every Thursday. Not on camera anyhow," Galecki wrote.

The episode, titled "The Gates Excitation," will reportedly feature Penny (Kaley Cuoco) getting the opportunity to host Gates as he looks to potentially partner up with her pharmaceutical company.

CBS' synopsis of the episode reports that Leonard (Galecki), Koothrappali (Kunal Nayyar) and Wolowitz (Simon Helberg) "do everything in their power to meet him (Gates)" while Sheldon (Jim Parsons) thinks the whole thing is one elaborate April Fool's prank.

Gates took to social media to tease the episode with the same photo, writing, "I had a lot of fun at @bigbangtheory. Luckily, I packed an extra tie."

I had a lot of fun at @bigbangtheory. Luckily, I packed an extra tie. pic.twitter.com/dAS2O4ihus

— Bill Gates (@BillGates) March 28, 2018

Gates joins an extensive list of celebrities that have made guest appearances and cameos on the comedy hit. Others include Buzz Aldrin, George Takei, Katee Sackhoff (usually in one of Wolowitz's dream sequences), Leonard Nimoy, LeVar Burton, Stan Lee, Sara Gilbert, Stephen Hawking, Adam West, Bill Nye, James Earl Jones, Carrie Fisher and Elon Musk.

The Big Bang Theory episode will air at 8 p.m. EST on Thursday on CBS.

Galecki was conspicuously absent from the premiere episode of the Roseanne revival this week, even though he was a staple on the show for five years in the 1990s. But fans won't need to wait too long to see him, as he's reportedly set to appear in the sixth episode of show.

The Big Bang Theory actor has also found himself battling back against social media criticism over voicing his opinions on gun control, calling for more background checks following the Parkland Shooting back on Feb. 14.

To the people who lashed out and unfollowed him on social media, he says "good riddance."

"In my last couple of posts, I've not suggested a single idea for new gun laws or background checks or even mental illness issues after the latest school murders in Florida. I only suggested change. And yet many folks were outraged and threatened and angered by only that," the Big Bang Theory star wrote on Instagram. "They unfollowed my account (fine). Or remained to convince me to [pack your bags] REALLY? You feel there's zero change needed? You hate and want me out of the country and belittle my opinion after three generations of my fathers served and gave their lives because I suggest it's not shameful to maybe explore taking a page from another country where their children haven't been mass murdered in a school shooting in over 20 years?"