Edit:Just looked it up, it means embarrased if it is followed by "grin" otherwise the explanations more towards shy are correct.
I refuse to give any of them the dignity of being called by their right names, thus, I mess them up. On purpose.
My favourite name together with foxglove (which in my language is closer to its latin name. Vingerhoedskruid, which means thimbleherb, but word for word, fingerhat (yes, that is what we call a thimble :P) herb. And it is digitalis in latin.
From Merriram-Webster's online dictionary: sheep·ish adjective \ˈshē-pish\
: showing or feeling embarrassment especially because you have done something foolish or wrong
It is a wellknown poison so it is bound to have found it's way to literature and tv/movies.
Plus, it's a cool word ;)