This way isn't effective but I've seen some people spam using it. I'd only recommend this if you're severely retarded and can't do it any other way.
1. Copy someones name.
2. Go into steam options and paste the name and add a bunch of spaces to the end, delete one space, then any character at the end. Press enter.
3. When mic spamming it's hard to tell the difference between you and the original.
Works best with names less than 10 characters.