Warning: NSFW
I can only image in the 'Waiting for pizza sex' scenario the pizza arrives when you are still in coitus.
Edit: I have also noticed the Goomy picture frame in the same panel.
Based on the laws of porn movies it means that the pizza delivery guy/girl gets in because you accidentally left the door open and after a brief voyeour scene the delivery guy/girl joins you in a threesome.
IRL on the other hand, it is more likely they will be ringing the doorbell for a while and you run to the door sweaty and red cheeked, just barely dressed and have an awkward time as you pay for the pizza.