In poker, stands for Fancy Pants Syndrome, or alternatively, Fancy Play Syndrome.
If you're constantly getting fancy, betting in a non-standard and deceptive way rather than value-betting your good hands and checking/folding your bad ones, you're probably suffering from Fancy Play Syndrome. Especially if it comes back to bite you.
Why did you check the nuts on the river in this hand? Looks like you're suffering from a case of FPS.