I work in an open plan office and the woman opposite me constantly has her feet under my desk! I often have my feet tucked under me but sometimes I want to stretch my legs out a little bit but her kicked off shoes or bare feet will already be there! 
I've started kicking her shoes back under her desk and not looking before shifting my position so if her feet get a kick too bad.
She's the open plan office nightmare - constantly muttering to herself, eats loudly, types loudly, holds long loud personal calls then tolls her eyes when asked to doe something like send a letter! Pisses me off no end.
Aibu to get some steel capped boots?!