Question

The boy was too fool to understand his jokes. (Omit 'too')

Answer 1

The boy was very fool to understand his jokes.

Answer 2

Omission refers to the something which is neglected, missed out or not done.

When from the above sentence 'too' is omitted it would be written as:

The boy was fool to understand his jokes.

'Too' is omitted in the above sentence because, 'too' as an adverb is used to indicate something negative. Therefore, the above sentence does not imply the boy to be fool in every situation.