BEING here means ACTING or BEHAVING stupid in a certain situation. Eugene's translations speaks of someone who is generally stupid, and that's not what this implies. An intelligent, sensible person can behave stupidly: "The professor died in a car accident. He was texting his wife while driving home on the interstate. Can you imagine anyone being so stupid?"

We often use BEING to describe someone's behavior. https://www.google.com/search?sxsrf=ALeKk03wSiMR8DsPuaDg2vPVcGhKyAIXtg%3A1598186752822&ei=AGVCX8PcMbCvtgXKiLMI&q=%22he%27s+being+really%22&oq=%22he%27s+being+really%22&gs_lcp=CgZwc3ktYWIQAzICCAAyBAgAEB4yBggAEAgQHjIGCAAQCBAeOgYIABAFEB46BggAEAcQHjoKCC4QxwEQowIQQzoNCC4QsQMQxwEQowIQQzoHCC4QsQMQQzoICC4QxwEQowI6CwguELEDEMcBEKMCOgUIABCRAjoECAAQQzoFCC4QkwI6CgguEMcBEKMCEAo6BAgAEAo6BwguEEMQkwI6BAguEEM6BQgAELEDOgUILhCxAzoCCC46BwguEA0QkwI6BAgAEA06CAgAEAgQBxAeOgoIABAIEAcQChAeOgoIABAIEA0QChAeUNuACViJkQlg4pMJaABwAHgAgAGEAYgB0Q-SAQQ2LjEzmAEAoAEBqgEHZ3dzLXdpesABAQ&sclient=psy-ab&ved=0ahUKEwjD3L7NrbHrAhWwl60KHUrEDAEQ4dUDCAs&uact=5

Можешь себе представить, чтобы кто-нибудь/кто-то отмочил такую глупость/так сглупил/протупил?

Yes!

It’s about the behavior/act, not the person

+++Alex!

This is more of an exclamation than an actual question, so your translation is perfect!

😌🙏