I told my friend I was going on a trip to Switzerland.

This joke is a delightful piece of wordplay, specifically a pun that combines a visual element with a common idiom. The humor hinges entirely on the word "plus" in the punchline. When you think of the Swiss flag, you immediately visualize the prominent white cross against a red background, which is, quite literally, a big plus sign. The joke then cleverly twists this visual into the everyday meaning of "plus" as something positive or beneficial, creating a simple yet effective comedic payoff.

Switzerland itself is a country rich in iconic imagery, from its majestic Alps and precision watches to its delicious chocolates. While many might instinctively think of Zurich or Geneva as its most prominent cities, Bern is actually the federal city, often referred to as the de facto capital. The friend's question about visiting the capital sets up a factual expectation, which the punchline playfully sidesteps, redirecting the audience's attention from geography to a universally recognizable national symbol.

The brilliance of this joke lies in its elegant simplicity. It leverages a widely known visual (the Swiss flag) and a common linguistic expression to deliver a quick, satisfying chuckle. It's a testament to how combining a straightforward image with a clever twist of words can create genuinely entertaining humor, making the flag not just a national emblem, but also a source of a good laugh.