Please note: This was written in a comedic manner as a reply to the prompt 'describe aliens attacking the Earth'.

If the aliens were hostile:

ARHHH!!! Humans shall fall!
Kablooey! The aliens are 10 ft tall!!
EXPLOSION! There goes the mall!

If the aliens were cute, but hostile:

Aww! They’re so cute!
Kablooey! The dumb humans should be mute!
SHAZAM! We shall collect our loot!

If the aliens looked like humans:
note: read this part in a British accent

Oh, allo chap. It’s a pleasure to meet you.
Kablooey! Well, I took care of you!
*puts away sword* That’s one less thing to do!

If the aliens were dogs:

ARFF! WOOF! ARFF!

Onto you we shall barf!

AHHHH!!! ARFF!

Oh, and Kablooey!