One of the most important skills a DM/GM/Narrator can have is the ability to make shit up on the spot. The simple fact is, if you want to run an entertaining campaign, you absolutely have to have this skill. In my last full campaign, a normal whore house turned into an immense boss fight with a demon constructed of corpses of whores just because one of my players rolled a 20 on his perception check. Here are a few tips to help perfect this art.
1. Know all the parameters of your campaign/session. It becomes difficult to think up random things on the spot if you don’t know what fits in the environment you’re working with. Keep things like lore, landscape, and climate in the back of your mind at all times.
2. Plan the unplannable. Always understand that players will undoubtably ruin your plans. Brainstorm in your free time about countless possible backup plans or insertable scenarios. This will allow for “This is a good time to try out this encounter” moments.
3. Take improv classes. Countless DM/GM/Narrators will give you this advice. It is a brilliant way to prepare to wow your players with random bursts of creativity.
4. Use homebrew content. With homebrew content, you will understand the possibilities far better than anybody else, and it will constantly leave your players guessing.
In a lot of ways, bullshitting relies on natural talent. If you follow these tips however, I believe you’ll be able to develop this skill and provide a unique and entertaining game for your players.