Why did Stacey and the go into the Wallace store even though they knew they'd get whipped

TJ is a bad influence on Stacey. TJ entreats Stacey to join him at the Wallace store despite Papa's threat of a whipping if he goes there. At this point in the story, Stacey is still impressionable and wants to so TJ that he is no coward.

despite being friends, tj is not a good influence for stacey. tj tells stacey to go and he doesn’t back down because he doesn’t want to look or seem like a coward. he knows deep down that if he’s caught, he will be whipped, or “worn out”, but he still makes the decision.