I am trying to prove a theorem (title) given in a starred problem in Sipser's book. I have absolutely no idea how I would go about showing it, and after trying a few different approaches came here looking for a hint. I don't want a full answer, but would really appreciate a few words to point me in the right direction. This is not a homework exercise.
Prove $\forall c \in \mathbb{N} \, \exists x,y \in \Sigma^* \, [K(xy) > K(x) + K(y) + c]$
information theory;kolmogorov complexity