Somewhere behind a closed door, foster puppies were crying. The resident golden retriever heard it, and instead of ignoring the noise, he went and gathered supplies: a few toys, a shoe, and a bra.
Nobody knows why he picked those particular items. The toys are easy to explain, since puppies love to play, and the rest is a mystery. Honestly, the mystery is the good part.
What this means for your dog: dogs notice distress, puppy whining included, and plenty of them try to do something about it. That is one of the quieter reasons a resident dog is so useful in a foster home. Adult dogs teach puppies bite inhibition and manners in a language the puppy understands immediately, and foster homes are often what keeps a shelter from becoming a long-term kennel.
It is also worth remembering that the resident dog needs breaks. Give yours a gate or a room to retreat behind when the puppies get to be too much, and keep some one-on-one time in the daily routine. If your dog turns into a comfort-item delivery service, trade the shoe for a durable toy, because shoes and socks can be chewed and swallowed.