That is a very weird phrase. Sounds like a child who makes a tower of building blocks and then knocks them over with his butt when he turns around. Not a standard expression in German.

Sounds like a child who makes a tower of building blocks and then knocks them over with his butt when he turns around. Perfekt, das ist genau, was die Redewendung ausdrücken soll: to act clumsily / maladroitly.

Not a standard expression in German. Falsch. Vielleicht auf die Generation 40+ oder regional begrenzt, aber durchaus üblich und für jeden verständlich.

Maybe good old Lenin can help - "One step forward, two steps back"
(With him, it's always...)?

Und ich kenne den deutschen Ausdruck auch.

Thanks for the tips. At first I thought "Like a bull in a china shop", and then "the right hand doesn't know what the left hand is doing", but neither one captures the sense very well. I'll probably just have to use a figurative translation.

Der deutsche Spruch heißt eigentlich "Mit dem Hintern einreißen, was man mit den Händen aufgebaut hat".

Suggestion: to spoil/to destroy/... one's own hand(i)work