In an imbecilic way.

The quality of being imbecile; weakness; feebleness, especially of mind. / Something imbecilic; a stupid action, behaviour, etc.

plural of imbecile

like or as an imbecile; so senseless as to be laughable; absurd, foolish, stupid, idiotic.

plural of imbecility

(obsolete) A person with limited mental capacity who can perform tasks and think only like a young child, in medical circles meaning a person who lacks the capacity to develop beyond the mental age of a normal five to seven-year-old child.

(dated) Destitute of strength, whether of body or mind; feeble; impotent; especially, mentally weak.

In an imbecile manner.

imbecility