"He’s not used to speaking in public. I hope he doesn’t fumfeh when he gets up to the podium." (JPS)

"Most people who know Yiddish will fumfeh around and probably give up when asked, ‘How do you say three coins in a fountain?’… 'The answer is very simple: three coins in a fountain = ‘oysgevorfeneh gelt' (wasted money)." (source)

“Don’t let him fonfe on the amount.” (NJY)