Fam

Fam is a short for the word "Family". It's used when you trust someone like they are a part of your Family.
Fam also can stand for "Friends Always Matter" but not used as often

"Hey Dude. Can you get me McDonald's ?"
- "Sure Fam"

Light

Light is a Electromagnetic wave.
Lights as an adjective is the opposite of heavy. Which is easy to (push, Pull, Hold, Throw, Etc.)

"Dude i cant see anything"
- " I see a light !"
Or

"It's very light.. I can do that !"