B1A4 Gongchan revealed a self-claimed 'rare' photo on his twitter account of Jinyoung and CNU. On June 28, he uploaded the photo and wrote, "Rare item. A once in a lifetime photo. CNU hyung lost in a bet."
In the photo, CNU is seen piggybacking Jinyoung which the later apparently enjoying his ride. Fans who saw the photo expressed, "That's so cute!","I want a piggyback too!","I wonder what kind of bet it is." and so on.
Source: Gongchan's twitter