According to ComicBook.com on Sunday, "The Walking Dead" and "Guardians of the Galaxy's" actor Michael Rooker explained the reason for Yondu's smile at the Wizard World Chicago Comic Con. This revelation may be considered a movie spoiler to some, but it does bode the question as to why Yondu of the Ravagers would be smiling as he opened the orb up to only reveal a toy troll.
Near the end of the film and the battle with Ronan the Accuser and his allies, Yondu approaches Star-Lord demanding the orb containing one of the Infinity Stones. As Peter Quill gives him the orb, he vehemently reminds Yondu not to open the orb as his cohort grins and points back at Quill, smiles and walks away.
Back on the Ravager's ship, it appears that Yondu looks as if he smells a rat and the audience finds him staring at the orb with suspiction. He opens it up and sees the 80s novelty item in the orb and Yondu gets a big cheesy grin on his face. This would lead people as to why Yondu exposed the inside of the orb to his entire ship regardless of what Star-Lord told him. Though this may be telling of the kind of history he's had with Peter Quill as he could have been a victim of his shennigans on more than one occasion.
Later at a Wizard World Chicago Comic Con, Rooker explains the situation in that scene of the movie. Rooker explained that he thought this was some kind of right of passage for the youngster and figured Quill will be okay on his own without any kind of adoptive parental intervention.
“The thought in my head was that’s my boy. That’s my boy. I taught him well. He knows how to do it. He can survive now, you know. All that went through my head.”
James Gunn's "Guardians of the Galaxy" is in theaters everywhere and this weekend turned out to be number one at the box office.