[rzzzt]

From the submission:

  > For example, imagine when a worker processes a message, it performs 
  > a side effect like sending an email. It very well could receive the 
  > message, send the email, but then due to a network error fail to 
  > acknowledge the message.

Since we are now deeply in "explaining the joke"-territory: in this reply I am pretending to be a message queue implementation that never receives the ack from a receiver. Counting the vast number of upvotes on the comment, at least one other person was deligthed by this chain of replies with the subtext being apparent. I have also found your parent comment worthy of a sensible chuckle for the same reason.