You wake up tomorrow in the middle ages. What do you do?

This came up in the pub a while back. Say you wake up tomorrow and you inconveniently travelled back to medieval times with no way home and armed with nothing but your knowledge on the modern world, what would you do?

Even getting food and shelter would be a major challenge...you're hardly gonna waltz (hasn't been invented) into the nearest town and expect any help from the locals. They'd probably be livin from one harvest to the next hoping a major catastrophe, like a mild frost, doesn't wipe them all out.

Try talkin to them and they'd struggle to understand you. Presumably no one here speaks fluent middle Irish so the best case scenario would be England, but even then their English would probably be unintelligible (considering Shakespeare would be writing at least 100 years later). Even if they did understand you, your story would seem like a maniac's ravings or heresy. Likely to see you end up on the wrong side of a good flaying.

Longterm, could you use your knowledge of science etc. to your advantage? Say you get pally with the local duke:

"Yes, nephinbeg, this steam engine you keep rambling about would make me the richest noble in the kingdom. A fabulous idea. Can you build me one?"

"I have no idea how to cast iron, or how a high pressure steam engine works apart from heating up water and the steam running a piston. I also notice that ye're not big coal-men in this neck of mercia"

"That's a pity. How does gong farming sound to you?"

Say you were a mechanical engineer and you were able to follow through with all your fantastical technological claims, what then? What would you spend your new-found wealth on? Castles? (lovely drafty uncomfortable castles), Women/Men? (Your own toothless, malnourished, filthy, smelly harem), Food? (along with nightmarish diarrhoea), Luxuries? (you'd probably have to invent them all first).

It'd be pretty horrible alright. Does anyone think they could make a better situation out of it?