Code that may or may not pass muster

I know we've got some computer science students in here, and I know you've written some questionable code at 2:30 in the morning before your project is due. So post it here! Preferably one-liners. Here's mine. I'm interested to see what my prof thinks of it... opinions could differ.

printf("%.1f%c", *e, (0 == (e - matrix + 1) % size)?'\n':'\t');

printf
Problem found! printf will bottleneck your code, especially when dealing with matrixen'