Original sentence: One variant, unusual in that it is as often as not used in the first person, past tense, to signify one's befuddlement or perplexity, is "didn't know whether to shit or go blind.Similar expressions include doesn't know his ass from a hole in the ground, doesn't know his ass from his elbow, "doesn't know his ass from left field," or Sir Henry Wood's doesn't know his brass from his woodwind