Has there been a rapture for one?
Was it faster to run without them?
Did he buy a new pair and not feel like carrying the old ones home?
Did they walk away on their own?
Is an invisible man dancing?
Was superglue spilled in the gutter right before he stepped into the street?
Have his feet grown two sizes in twenty minutes?
Is it an offering?
Writing prompts can be found anywhere. Sometimes you just have to look down.