Boil a large pot of thoroughly salted water. Once boiling, add the spaghetti. Cook the pasta 1-2 minutes less than the package states to get to an al dente texture. Once finished, strain the pasta and save one cup of the pasta-cooking water.
Heat the olive oil and butter in a large saucepan over medium heat.
Once the oil and butter are hot, add the onion and cook for 3 minutes, stirring occasionally.
Add the sliced hot dogs and cook for another 3 minutes, stirring often, until the hot dogs are slightly browned.
Add the bell pepper and mushrooms and cook for 4 more minutes, still stirring occasionally.
Add the minced garlic, stir, and cook for 30 seconds.
Add the ketchup and worcestershire and cook for 1-2 minutes, stirring constantly, until the sauce thickens.
Add ⅔ cup of the pasta-cooking water and the milk and stir.
With the saucepan still on medium heat, add the cooked spaghetti to the saucepan, and toss the pasta with the sauce to combine. Cook it for 1 minute, tossing constantly.