SZ once asked what f/u was, when I used it in an earlier entry. Bump replied her comment/question for me; I stopped commenting on my own blog already in case you haven't noticed..
So, one day, I picked up a call to hear a giggling colleague..
A: In your email subject, what does f/u stand for?
mf: Follow up..
A (to B in the background): FOLLOW UP!
*B took over phone**
B: A thought you were scolding me..
mf: *blur* Huh? *A and B laughing at the other end* .. .. Oh dear! I didn't think it would be mistaken!
B: A is too free..
A: I thought you were scolding B..
mf: If I wanted to scold him, I would use capital F!
A: Haha, I'll tell him that!
On retrospect, I think I'll just spell it out in full :p