This trope is about serial protagonists (mostly in adventure novels) who have items in their private collections which are continuity nods to previous adventures. It will only be mentioned in passing and completely confuse the secondary characters who come across it, but fans will recognize it instantly.
- The Ur Example is Clive Cussler's Dirk Pitt, who has a cast-iron bathtub rigged with an outboard motor sitting in his classic car collection. It's very out of place, but anyone who read Cyclops will know exactly where it came from.
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