1. Refers to the male genitalia or penis. used by men to describe their own genitalia usually in reference to how big it is or how useful it is or just to sound manly!
2. Also used as a verb 'to twang' meaning to fuck someone or have sex with someone. Used only by men in the respect of them using thir twang.
'i stuck my twang in her'
'my twang is so big'
'careful of my twang!'
'i wanna twang her!'