Perception and desire comes at the in between the lines of
"She has cooties but maybe I want them."
That day in class when the girl with the funny nose is the only one you want to hear when you tell your "best friends" that joke your Uncle Tom told you.
Likewise it was highly inappropriate and vulgar for the funny nose girl but in continuous;
Perception is seeing the funny nose girl as The Funny Nose Girl.
Desire is wanting to touch you're not so humorous nose against hers.
Not such a funny nose now is it kid?