Every time Zac Efron lets him down, a part of Mark dies.
Mark always had a bit of a soft spot for Zac Efron and his wonderful hair, primarily down to his affection for the High School Musical films. During a screening of The Life And Death Of Charlie St Cloud, Mark was so appalled that he was missing out on a good foot of Efron's hair because the projection was in the wrong ratio that he went out and spoke sternly to the assistant manager, who was spectacularly unbothered.
This was all until Dirty Grandpa was released, of course. The special relationship is now officially over.