Stereo sound via mono input

Yeah, so this is probably a stupid question, and I SHOULD know the answer but, again, I'm an idiot.

Is there an adapter that lets me take my two-channel outputs from a gaming system or other auxiliary device and route them BOTH into the mono-input audio channel on my TV?  Right now I'm using only the left channel, but I'd like to be able to hear them both without having to a) buy a new TV or b) use magic.  Routing to a stereo system is out of the question because this thing doesn't have any audio-out ports.  It's THAT old -_-

I'm not sure one exists, in any case, your game system and the audio receiver you have should both use 3.5mm stereo as it is the superior port.

But you're playing on a tv so, fail.

I assume you are using RCA connectors. Go to a dollar store and buy an RCA splitter. You may need some male-to-male adapters.