Some say it means “ring exchange” (not the wedding kind). Others say it means being chicken shit.

With Slovakian deal, Germany expands three-way ‘Ringtausch’ dance to arm Ukraine – Under the Ringtausch program, Germany has sent newer equipment to Slovakia, Greece, Slovenia and the Czech Republic, with those countries shifting older gear to Ukraine.
The Germans have a specific word for an exchange between at least three parties: “Ringtausch.” So it makes sense that is what the German government has named its procedure to gift modern military equipment to former Soviet-bloc countries who, in turn, gift their Soviet-era equipment to Ukraine.