First shake

Today I had 2 large cups of proper coffee-shop coffee and I got the shakes an hour later. This has never happened to me before and happened because I don't have a job and therefore don't have enough caffeine in my life.

P.S. The title of this post sounds like it should be a pun, but I'm not sure that it is. If you recognise the intended pun, please explain it to me... Thank you.