They were at the '2017 Melon Music Awards' and it sounds like they were possibly hanging around where the fans wait for their idols leaving and arriving. They were holding their EXO lightstick, and when Kwon Hyun Bin and Takada Kenta saw them from inside their van, they rolled their window down to congratulate the fan.
They wrote, "Just now, JBJ members rolled down their window and saw me with the EXO lightstick, and told me congratulations ㅠㅠㅠㅠㅠ Thank you so much ㅠㅠㅠㅠ I think it was Kwon Hyun Bin and Kenta..? They had their hair dyed. Thank you, really ㅠㅠㅠ I'm getting my faith back in humanity." They added, "I hope JBJ fans will see this, really. I enjoyed JBJ's performance," and again, "Since this is getting RTed, I want to add that their heads were so small... Like... really... really... I thought it was going to fit in my hand... Anyway, thank you... JBJ's song is so addicting! I hope they do well."
As awards season can be a bit of a sensitive time for fans, it's nice to see idols take the lead and interact positively with other groups' fans.