Fog up

The act of smoking marijuana. So much marijuana is smoked that the area resembles an outdoor bog. A foggy bog.

Example 1: OH, man, I'm so burnt out. We fogged up last night; I ate a Hot Pocket straight out of the freezer.

Example 2: Wanna fog up after class? We can watch my cats play in my backyard.

Let's fog up the windows

To have sex in the car.

Hey babe, let's fog up the windows tonight!

Fogged up

When your brain is all foggy and you have a hard time separating the concrete & abstract.

Side-note: Fogged up is also how Danish people pronounce "fucked up".

As Alice came to her senses her head was a bit fogged up from the accident, it felt as though she was still in wonderland, but had a hard time discerning what was real.