Yup is an expression used to state or Confirm a fact. It can have the meaning of "yea”, “I understand” and other corresponding terms, as it can also mean “no” in some cases.
In a communicative act, it has the function of keeping the communication path open, showing the interlocutor that he is following the conversation (this does not mean that he is interested in what the another speaks). In language it performs the phatic function.
In certain situations it can be used ironically, as is the case of the expression “Aham, I know”, which is used to show distrust or disbelief in what the interlocutor says.
The word "aham" is also associated with the expression "Aham, Claudia, sit there", which became popular through a video posted on the internet and starring the presenter Xuxa, at the beginning of her career.
In the video, one of the children approaches to tell you or show you something. But, flustered by the restless children on stage, Xuxa turns around quickly and without paying much attention to what the little girl intended.
The expression became popular and started to be used when the listener is not very interested in what the interlocutor says, ignoring their comments.
“Aham, Claudia, sit there” is an example of a phrase that has become an internet meme.