Like I speak English and Portuguese, learning Dutch, and (not doing it for the sake of a primarily English-speaking community) but I will often switch between the two, like saying “Bom dia/Oi” to someone or “Tchau!”
I may also falar assim and I don’t do it to show off, it’s just comfortable pra mim. I will mix in a few português words. (Not exactly like this but YKWIM, maybe).
English, Spanish/Spanglish, and a bit of French. Parfois, I like to cambiar idiomas dans le middle of une phrase to mess with mes amigos. But yes I always mix up things. The most common is when I accidentally inject Spanish into French