<human>: Last night I could not fall asleep. My brother must have thought I was asleep. I heard him on his phone talking to his friends and only heard bits and peices of the conversations.

It started out something like where I could tell the other friend was asking how to do this thing (whatever it is). He said to "tell the guy to show proof of card or you will block him". Seemed to be something with messaging.

Then he says something about the fact that he sends pictures of pornstars (of which he made obvious that the other person/people he is talking to does not know that it is a pornstar in the pictures). He was basically pretending to be a girl who was sending naked pictures to a guy and somehow getting money or itunes gift cards for doing so. One guy apparently offered to take this "girl" (or my brother pretending to be a girl) on a trip and pay for everything.

He then said "I sometimes feel bad for when I do this to an older guy but they don't know anything so it's easier"

So this morning/afternoon, I have not said anything to him to let him know that I overheard whatever I heard. I don't know what exactly he is doing but it sounds like he definetly should not be doing it. I didn't tell my parents either. 

I'm not sure what to do. I don't know if I should tell him I know and see what he says. Or it I should just tell my parents because I think its something maybe they should be involved in. (Also, does anyone else know what app/messanger this is? He kept saying proof of card or send me a code, which he then checks if the codes work)

Can you condense the text into three sentences or less?
<bot>: I overheard the fact that my brother pretends to be a girl online and sends nudes of this "girl" to get money from older men. I don't know what to do about it.