IFrame: This content cannot be displayed in a frame

I have two internal sites. I’m trying to show one’s content in the iframe of the other site. However I’m getting this message: “This content cannot be displayed in a frame.” I’ve read the reason I’m getting this message but, I would like to bypass it since the sites are internal and I’m not concerned with someone trying to hijack my users. I couldn’t find a way to bypass it after searching the internet, but feel like it should be possible because the rest of the message seems to hint at it.