Inside the booth
Let only part of a prop enter the frame
Create a visual question without hiding the portrait.
A partial object at an edge can make a sequence feel playful.
Test the crop deliberately
Use a safe lightweight object and decide which part should appear. Keep faces within the portrait windows and leave enough information to recognise the object if that matters. A camera preview may differ from the strip crop, so inspect an actual export before planning the full sequence.
Make a clear ending
Reveal more of the object in a later frame or leave the question unresolved intentionally. Review the sequence without a long explanation. Preserve an ordinary portrait as an alternative if the visual joke works only with a caption that nobody can read at the final size.