DAVE: You know, my parents would love these sandwiches. I wish I could bring them by but unfortunately they’re in private Bible study right now.
Dave shows Lane how interested he is in her, and how keen he is to impress her rather scary mother, by coming over to eat her fake egg sandwiches. Just in case you’ve forgotten, it is now past five in the morning! Who even wants sandwiches at this hour? Why is Mrs Kim still serving them? The filling would have gone off by now, and she freely admits herself the bread is stale.
He also pretends that he is a Christian, as a way to inveigle himself into Mrs Kim’s good books. He claims that his parents would be joining in the stale fake egg sandwich celebration, except that they are in a private Bible study session. At five in the morning??? It would be far more believable to say they were asleep!
Later he says his parents are at church (at five in the morning!), which means the fictional Bible study session wasn’t private at all. Dave’s story has more holes than Swiss cheese, but Mrs Kim, always shown to be pretty switched-on previously, is swallowing this farrago of lies like a gullible fool. She must be very, very tired. Or she really likes Dave.