TSK · Judges 18:3

then they said to him,“Say‘Shibboleth!’” If he said,“Sibboleth”(and could not pronounce the word correctly), they grabbed him and executed him right there at the fords of the Jordan. On that day forty-two thousand Ephraimites fell dead.

After a little while, those standing there came up to Peter and said,“You really are one of them too– even your accent gives you away!”