No known anime matches this exact phrase. However, several tropes overlap:
There’s a certain magic to overnight stays (otomari) when you’re a kid — or even as an adult. But when it’s with a cousin (shinseki no ko), things get extra special. Add “dub” into the mix, and you’ve got the recipe for a cozy, chaotic, nostalgic night in. shinseki no ko to o tomari dakara dub
Dakara means “so” or “therefore.” So:
Shinseki no ko to o tomari dakara dub.
“So, because I’m staying over with my cousin… dubs.” No known anime matches this exact phrase
It’s a non-sequitur that makes perfect sense to anyone who’s ever shared earbuds, argued over which episode to skip, and fallen asleep mid-way through a Yu-Gi-Oh! or Sailor Moon dub. argued over which episode to skip