"bitch switch" - the thing you say to your partner that makes them go off when everything was fine right before you said your idiot remark.
"Buckle up" may mean "fasten your seat-belt because you are in for a bumpy ride".
The whole slogan may mean "You just said something to annoy me, and now you're going to pay for it." But please wait for an answer from someone who may know what they are talking about.
An aside: "Buckle up buttercup" is taken from the lyrics of the Fresh Air song 'Fast car' (meaning: Put your seatbelt on, you're in for a bumpy ride, i.e. something unpleasant is going to happen to you). And that's surely a reference to the famous Motown song 'Pucker up Buttercup', where Buttercup is just a name.