An Astros Minor Leaguer fell victim to the classic bubble-gum-on-the-hat prank

What do you say to a guy, like Astros Minor Leaguer Andrew Aplin, with a bubble-gum bubble stuck on his cap? He sits there, unaware there is a translucent pink blob adhered to his head -- if it were any bigger (and filled with helium), it would lift him right up into the stratosphere. Assuming he didn't put it there himself (unless he did, and this is all some sort reverse-gaslighting), the bubble could very well stay there until, well, forever, maybe.
So, do you tell him? Do you play rock-paper-scissors with the guy next to you to see who has to come clean? Do you tap him on the shoulder, nod up to the top of his head, raise your eyebrows? Do you say, "Hey, buddy, you got something up top?" Do you keep glancing up, hoping he gets the hint? 
No, you say nothing. Ignorance is bliss.