A few winters ago over Missouri:
"Delta 246, climb and maintain FL350. Traffic three o'clock, 20 miles at FL310."
"Roger. Delta 246 departing FL310 for FL350. We see traffic at our nine o'clock position, level."
"Ahh roger, Delta 246. That was three o'clock Zulu, nine o'clock local."
"Nice recovery, Center. In sight off our left wing. We're climbing to FL350."