Can you put android on an iPhone 4S?

Just wondering, because I want an android phone, but I can't afford a new phone.

No. They work on different OS

Is this a joke?

Course not.

I'm not saying it is not possible, but it would be very hard to manipulate. Years ago, there was a piece of software downloaded via cydia called, "Bootlace." If you were able to get it to work, you could install Android 2.2 froyo on the iPhone 3G. Pretty cool right? Unfortunately though, it only worked on the 3G. How long have you owned your iPhone? If you have owned it for 2 years+, sell your iPhone on eBay and you will probably end up with enough money to buy a new phone on contract. I would recommend getting a Note 3, a GS4, a G2, or a Nexus 5.

No, because there's no existing ROM build for Apple devices, nor any drivers exist for it that would work on Android. If anything, the only ones that could dual boot are the older iPhones from 3GS and older. But even then, it would require heavy modding and compatibility may not be guaranteed.

Yes you can but you have to pray to Satan first.