It's not all that uncommon to see sitcoms and procedurals crossover over with other shows in their particular arenas. When it comes to the former, one can look to the occasional mashups between Everybody Loves Raymond and the King of Queens or Family Matters character Steve Urkel's appearances in fellow TGIF sitcoms. As for the latter genre, characters from various Law & Order shows have crossed paths, and the One Chicago franchise sees its key characters have frequent run-ins.

Despite all that though, it's not so typical that a multi-cam comedy and single-camera drama cross the aisle and mix it up. Yet that's what happened with CSI: Crime Scene Investigation and Two and a Half Men.

Yes, you read that correctly. Those two shows did indeed have a crossover – but not one that was as straightforward as you're probably thinking. (No, Charlie Sheen's Charlie Harper did not try to wine and dine Marg Helgenberger's Catherine Willows.

) Nevertheless, it was still quite a feat, as it required keen collaboration amongst the writers and producers of both CBS shows. So when and how did all of this unfold? Well, let's talk that out.

Who Got The Ball Rolling On The Crossover Between Two And A Half Men And CSI?

So apparently, this unconventional mashup was initiated by Two and a Half Men co-creator (and all-around super producer) Chuck Lorre in 2007.

He reportedly reached out to CSI executive producer Carol Mendelsohn about a crossover that would see their respective writing staffs pen episodes of each other's shows. Mendelsohn (via CBS News) was interested in the idea but wasn't sure if she, Lorre and co. would actually be allowed to proceed with it:

When Chuck pitched the idea to me … I thought it was an intriguing idea and walked into Naran's [Naran Shaknar, co-executive producer of 'CSI'] office and he said 'what a nut.

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