You've probably already been told this but many freepers type a BTTT so that they can come back later to their personal pings to continue reading the thread from that specific place (their BTTT).
Ah, I have seen "placemarker" or "sit-rep" or "bookmark" for that, but was taught "BTTT" means bump to the top, so as to have this thread appear at the top of the recent posts list.
In any case, i'll accept your explanation with a thank you.