Just watch the video and you’ll understand
Does this only happen if you do a dance emote first?
nope. i did the Emote that you can see the radio
did one of your multiplayer peoples put it on you lol
I’ve put them on multiplayer peoples flak mopeds before 
but never on the multiplayer peoples themselves
found it, when driving the flak-moped I deployed the field radio from the inventory menu,
and the field radio sticks to you, POP QUIZ: what happens when you fast travel to it
you will have to exit game to get the field radio removed 
even after all the uses of the field radio, it still stays sticking to you