Here is a very simple Kahoot rap for you. It utilizes mostly end rhyme and slant rhyme, so feel free to modify:
So,
you wanna be the leader of your classroom's kids,
study all night and become the whiz,
a square, circle, triangle, and rhombus
will determine if you truly are the smartest!

Kahoot! Let me hear you say: Kahoot!

Now even the teacher can't believe it,
as you climb to first place, bit by bit
They try to trip you, mix you, or trick you,
but all the right answers just seem to tip you!

Kahoot! Let me hear you say: Kahoot!

Here it comes, the big test day,
you won every Kahoot there is to play,
but you realized you made a fatal mistake:
You crammed too much, and it was all so fake!

Kahoot! Let me hear you say: Kahoot!

You struggle through the questions, one by one,
and begin the realize, you were pretty dumb,
the answers get harder, the quiz is smarter,
With your teacher, you'll have to barter!

Kahoot! Let me hear you say: Kahoot!