Someone is controlling my friends keyboardinputs

Hey,

my friends pc is behaving weird. It is typing on its own... real sentences and its getting scary. It is only at night and not all the time. Today it wrote:

"powww in luft jagen jaaa pimmel in MY NAME format pamela andersen gehstocklangstrumpf lutsch gerade aber krass"

Instead of MY NAME it wrote my actual name, my name can be written all kind of ways, so it is fucking creepy.

He is considering to reset his whole PC. Does someone have an idea what can cause this? Which possible ways can someone use to only write on someones PC?