Comically Misidentified Foreign Technology

A character finds Lost Technology and winds up completely, and hilariously, wrong about what it was intended for. Can also occur with contemporary technology if a character is from another time or world, or from a significantly more primitive culture. Often the technology is something real that the audience would be familiar with and immediately aware the character is wrong about, but other methods of revealing the item's true purpose are possible.

An Amusing Alien is likely to fall victim to this. If the technology is mistaken for a planet's rulers, it's Mistook the Dominant Lifeform. Can overlap with Mundane Utility if the misused item has a potent intended use. Can overlap with Low Culture, High Tech if a civilization uses the foreign technology they have acquired for an unintended use.

Examples of Comically Misidentified Foreign Technology include:

Film

In Disney's The Little Mermaid, Scuttle claims to be an expert on humans but thinks forks are combs called "dinglehoppers", and smoking pipes are musical instruments called "snarfblats".

Literature

In the Touhou short stories collection Curiosities of Lotus Asia, Rinnosuke Morichika (best known for being the only living humanoid man in Gensokyo with a name) has the power to know the name and purpose of an object by examining it. This ability would come in handy given all the items from the modern world outside Gensokyo that somehow find their way inside it but, unfortunately for him, this power doesn't let him know how to use an item and often leaves out critical details to the point he makes mistakes like thinking a Game Boy is a doomsday device.
The Motel of the Mysteries -- a book set After the End, "documenting" the archaeological exploration of a motel buried Pompeii-style by a Victorian-like successor civilization to ours -- is filled with hilarious misinterpretations of the devices and objects they find, starting with the conclusion that the toilet was an altar with a religious function.

Tabletop Games

The third edition version Mutants & Masterminds mentions that the need to identify technology works both forward (modern humans understanding future alien gear), and backwards with aliens needing to work out less advanced Earth technology "can lead to some mishaps and unintended comedy for aliens trying to live amongst humans.".

Video Games

In Shin Megami Tensei IV the player can find "Relic" items which have no purpose but selling. As the protagonist is a samurai from another world, and is traveling through a post-apocalyptic Tokyo, the descriptions of the items found contain some rather off guesses like thinking a hair dryer is a gun, or media discs are mirrors.
In the post-apocalyptic game Metal Max 2 monsters will occasionally drop a "Odd Balloon". This item seems innocuous (and is totally pointless aside from its small sell value), but the one with a fixed location in the game world is found in the ruins of what "used to be a hotel named LoveJoy".

Western Animation

In the Rick and Morty episode Interdimensional Cable 2: Tempting Fate, Jerry attempts to hold a group of aliens hostage with an equally alien ray-gun. Too bad said ray-gun turns out to be a prosthetic penis.

Real Life

In his autobiography, sakoku born English-Japanese translator Fukuzawa Yukichi (the man on the 10,000 Yen bill) recalls with embarrassment an incident during his first trip to the United States when he and his companions were served drinks with "strange fragments" floating in them and the various ways his group reacted to them in front of the high status hosts, with some trying to chew them, while others swallowed them whole. He was surprised when he found out they were ice cubes.
The Waste Isolation Pilot Plant hopes to avert this trope for future generations, and is developing a system of long-term nuclear waste warning messages that should be understandable even after all of the world's current civilizations are long-dead.
A running gag in archaeology circles, poking fun at their less-through and less-professional predecessors and colleagues, is that any item (or fragment thereof) that doesn't have a readily identified purpose get attributed to "ceremonial" or "ritual" instead of "unknown".
- A "mask" found at Teutoburg Forest suffered from this. Further examination revealed it was actually a removable part of a helmet, essentially a proto-visor.