nà huó er ( 那活儿 那活兒) = penis, usually seen in novels/fictions.'second in the family', 'little brother')
It was misinterpreted as luǎn ( 卵) by Mandarin speakers, though sometimes ' 卵' is used instead for euphemism. Slang words for the penis refer to it literally, and are not necessarily negative words: As in English, many Mandarin Chinese slang terms involve the genitalia or other sexual terms.
