to say or do something tactless or embarrassing:

I really put my foot in my mouth – I asked her if Jane was her mother, but she said Jane is her sister.

When I told Ann that her hair was more beautiful than I had ever seen it, I really put my foot in my mouth. It was a wig.

I put my foot in it by telling John’s secret; he found out.

These terms might not exactly trip off the tongue, but they could stop you putting your foot in it.

We had one conversation about putting your foot in it.

Speaking of sports ministers, it seems they all have a knack for putting their foot in it.