I think they've only really talked about it a few times, once that I know of was during summer concert MC when Jun was doing NatsuNiji and the other time I can think of that was especially hilarious was on the hidden track for the WISH single and Jun was doing HanaDan.

Just the fact that they run through Jun's bag when he's not looking often enough that this has happened more than once makes me incredibly joyful to be in this fandom. ♥