To 'get schwifty' is the verb form of MacGyver. To MacGyver is 'to make or repair (an object) in an improvised or inventive way, making use of whatever items are at hand'.
Rick tells Morty to "just hit a button, give me a beat" and then proceeds to make up a song on the spot. Rick being the filthy old man that he is uses the first lyrics that come into his head, "take off your panties", "shit on the floor". These are not what it means to get schwifty.
Oh man, my car tire is flat and I'm already late for work. It's time to get schwifty.
10👍 8👎