The following text is a valid DOS program:
X5M@P5~APZ%3@PY%AAP[5~$P^5T%P_)5GGG)5GG)5XPLFXLFLEQX5M@P5~APZ%3@PY%AAP[5~$P^5T%P_)5GGG)5GG)5XPLFXLFLEQ
What happens when you run it?