Respuesta :

This is a pun because the caption says "The streets were awfully deserted last night" which is "funny" because desserts are standing in the streets. 
HowDULL
"Deserted" relates to "empty", while "dessert" relates to a sweet post dinner treat. So, in the statement, one would assume that deserted related to an empty street, when in fact it related to Dessert-ed meaningful of desserts, which is the play on words.