Is it possible to make two phones interact by rubbing them against eachother?
Let's assume the technique is used to connect the devices via an app.
Give me all your alternatives if this isn't possible, I'm talking about connecting the phones via Bluetooth or something like that. Thanks.
The closest thing to what you're looking for is called Near Field Communication (or NFC).
Currently fully supported by many Android phones without major limitations. Apple devices are more limited in NFC usage (currently restricted to Apple Pay only).
For more information, read Near field communication (Wikipedia).