Calling a person a 'potato' (ziemniak/kartofel/burak)

That kind of indirect, metaphoric humour is the exception in Polish. I did use the expression - loosely translated* - once in conversation with the in-laws and it got a laugh, they knew what was being said; but I wouldn't bet money on it being an authentic Polish turn of phrase.

* think it went like this: on nie najostrzejszy nożyk w szufladzie - 'He's not the sharpest knife in the drawer'

"Jest bystry jak woda w kiblu" - vaguely similar ;)

Love it. Thanks, noted...

oh sorry, of course I was quoting "alijturner59" ;)

thanks frd - pls translate for a learner?!
and thanks alexw68, that's interesting about the metaphor gag being english
especially as i have come across some really fabulous similes such as eg for someone looking bemused - 'like a dog who's been shown a card trick'

makes me laugh every time

I dont know.... where live is someone calls you that is means your chubby and lazy

I prefer "Jesteś bystry jak woda w klozecie" :)