知ったかぶりをするのはおかしいです。


It's strange/odd/weird that you pretend to know about "X"


when/which you actually don't know about.


上記のほかにtalk about やspeak aboutを使っても、


ここでは同じ意味になります。


It's strange/odd/ weird that you talk about "X"


when/which you actually don't know about.


It's starnge/odd/weird that you speak about "X"


when/which you acutually don't know about.


pretend to know で知ったかぶりをする


weird も おかしいの意味です。