Hello B1957: Sure you can, but why would you want to? Just don't touch the two speaker wires to gather shorting them out, possibly damaging the audio amplifier transistor or chip.
There are great sounding speakers out there that will greatly enhance the sound that you don't need to experiment around unless you just want to. And in most cases just adding any external speaker usually sounds better than the mass produced minimum cost speakers used in the radios. Most all radios have a 1/8 inch mono type receptacle in the back of the radio just for the external speaker.
I like the Wilson Chrome Plated External Speaker, it sounds great and the its made from steel.
See:
https://www.bellscb.com/products/accessories/Speakers/All_Speakers.htm
Motorola External Speakers are all over the internet for sale that also sound great.
I use a Clear Speech DSP ( Digital Signal Processor ) External Speaker in my truck it removes some noised and sounds great, easy to use and install.
See:
West Mountain Radio - CLRspkr ClearSpeech® DSP Noise Reduction Speaker
Palstar makes a great sounded external speaker, not cheap but sounds fantastic.
See:
Palstar - Speakers
I also use a "Sonic Cushion" that levels out the different (low and high) volume levels heard from SSB (Single Side Band) Mode. The speaker wires are feed to a GE-47 Light Bulb, a 25 Ohm variable resistor is wired also across the speaker wires, one leg of the resistor and the middle wiper connection is then feed to the speaker or DSP Unit that's wired to the speaker. Works great!
Using head set is also a good call, when that far away DX station is hard to hear and doesn't want to reply to you.......
See:
Heil Headsets Technology for Amateur Radio - Heil Sound Amateur
Good luck, hope this helps.
Jay in the Great Mojave Desert..... just down the road ah ways from the fillin station, Miss Dinah has a price cut on gas, but the ammo and groceries are a bit steep