屎 is vulgar but common in daily speech. Used in many colorful expressions: 狗屎 (dog crap / nonsense), 放屁 is related but uses a different character. 屎 is also used figuratively to mean something terrible.
memory
The top part 尸 means 'corpse/body' and the bottom 米 means 'rice' — what comes out of the body after eating rice.