Use a microcassette recorder as a “vocal” mic.

The built-in compression on these devices is usually so crazy that it lends an interesting character to whatever you record into it.
I used this sound for the scratchy response vocal in the chorus of “Really Really Weird“:
Audio clip: Adobe Flash Player (version 9 or above) is required to play this audio clip. Download the latest version here. You also need to have JavaScript enabled in your browser.
Record onto the cassette, then play the tape into your DAW and line things up at the proper place in the mix.
Or, for a slightly cleaner sound, put the recorder into record mode and connect the headphone out jack into your DAW input. Then you can truly use the microcassette recorder as a real-time “mic.”