Random connection will be the 4U+ connecting to any NFC device. If your phone has NFC, just turn it on and bump them together. Won't do anything but your 4U+ will play some animation.
Oh... The only things with NFC that I have are the Wii U and my 3DS and they only connect to Amiibos. Can the 4U+ pick up on the Wii U connecting to an Amiibo?
I'm not too sure about it as I do not have them... but you can always try! Make sure the NFC on your wii is on. for the 4U+, you can just put it on the normal screen where it shows your character.