Welcome to FreeRepublic!
A 'bump' is like a 'ping'. Oftentimes, freepers will ask to be placed on a "common theme" list, in order to be notified when new threads are posted.
For example, you just arrived here today. You pulled up a thread that is nearly one year old. A more 'current' thread on this topic is this one ...
A Deacon's Comments on Mel Gibson's The Passion of The Christ
If you were on my bump list, you would have been notified.
Hang around here for a few days. You'll catch on!