when you 'check in' using the Facebook Places facility, but you are not actually at the place you checked into.
This could be to fool people into thinking you are in one location when you are in fact in a different location close by.
You might also do this to appear cool on facebook by checking into exciting sounding locations. It allows a person to 'check into' a bar or club near where they live, when they are in fact at home in bed.
You might also check in whilst in a car.... driving past a location. hence the definition of drive by check-in
A. Hey Amy.... just seen that you checked into "Sonic bar and Club"??
B. No i'm actually at the home.... did a cheeky check in at Sonic on my way past!
A. HAHA a drive by check-in you sly dog!