If they're the tie dye dungarees (don't use insta so I have no clue what they look like the ones you're questioning about, only going off one pair of dungarees I've seen Tan in) they're from Lucy and yakHer throwback child snaps do show she was adorable - Yo uTu be creates monsters!
I imagine she was sent the link to the film early to tweet / ig about having seen it so her millions of loyal followers (ha) would have their interest sparked enough to pay to see it. Doubt he checks his insta much anyways.
Anyone clock where the dungarees were from?