vpn over ssh proxy

I've the following problem:
I want to create a VPN connection to a friend of mine. Our PCs are
both behind a router to which we have no access to.
I thought about using a ssh proxy on a server, but the problem is,
that none of us has a server in the net.
Are there any servers which offer free ssh proxies?
Is there any other solution to get a VPN working between our two PCs
which are not directly visible to the net because they are hidden
behind a router?