'Rock paper scissors!' 'Rock!' 'Uh... paper!' 'Hey, that was after me!'
Literal
''Janken [emphatic-ね]'' ''Rock (gū)'' ''Wait... paper (pā)'' ''Playing-after [emphatic-かよ]!''
Janken (じゃんけん) is 'rock paper scissors'. The calls are グー (rock, 'goo'), チョキ (scissors), パー (paper). 後出し ('playing after') is the cheating move of seeing your opponent's move first. かよ combines question か with assertive よ to express disbelief or accusatory pushback. The ちょ... (short for ちょっと 'wait') is a stalling filler used when trying to buy time to cheat.