am I not supposed to eat this raw or something?

I only know of it from like, The Sopranos, and that it's slang for money in east-coast italian-american lingo. But I bought some the other day on sale, and thought that it just looked like lettuce, so I made a big salad 2 days ago, and since then, my stomach is cramping and generally foul and I hate life. Everything else I ate was from my normal menu options that I know cause no digestive problems.

So is this like a trick lettuce or something?