Piped up has several meanings in rap so read this article carefully. Also, note that the term has some negative or absurd uses.
Piped up might refer to getting angry or being pissed about something.
“He got me piped up after forgetting our anniversary!”
It may also be used to refer to one’s erect male genitalia since “pipe” substitutes the male sex organ.
“Every morning, guys would usually get piped up due to some normal biological processes.”
The term might also be used to say that you are heavily intoxicated or high due to particular substances.
“The party was wild. Some even got piped up too much. I won’t be surprised if some of them are still hungover up to now.”
Lastly, when used positively, it implies working out, grinding, and doing what is necessary for self-improvement.
“I need to be piping up every day if I want to become a millionaire.