A grave discovery

"You doing alright?" David finally asked as they reach what he estimated was about mile two.

"I'm fine." Laylah said. Her nipples must have started to become irritated because they were sticking out from her shirt more than they were before. David tried not to focus on them for too long and instead offered, "we could turn around at that stop sign up there and make our way back."

"No! We did that yesterday. Farther every day, that's what we agreed on, right?" Laylah said stubbornly.

"I mean, yeah but today's a little different don't you thi-" and before he could finish the sentence, Laylah said gruffly,

"Farther. Every. DAY." and at that last word she picked up the speed, blowing past David.

Her speed was remarkable, but that wasn't what got David's attention. Now that he caught sight of Laylah from behind for the first time today, it was all too apparent that something had gone horribly wrong. Back when she bent over to tie her shoes, that's when it must have happened...

David stared in shock at the gigantic tear in the back of Laylah's leggings. It ran from just below the thin elastic band around her waist all the way down to the middle of her thighs, it was coming apart at the seams! Laylah's bare but was completely exposed! wait a minute, BARE?! Oh god, Laylah DID forget to wear something today. PANTIES!

As the determined girl's shapely ass bounced as she sprinted, what did David do?