If you liked laurel/yanny, then you’ll love whatever this is.
Listen to the clip first, before reading on, so that you’re not primed.
Briefly: Grover says “that sounds like an excellent idea” and some folks hear it as “that’s a fuckin’ excellent idea”.
There are some differences between the laurel/yanny case and this one.
Firstly, there’s full context: it’s not just an isolated set of sounds, it’s a phrase being spoken on an American children’s television program, so we know there are no f-bombs being dropped really.
Secondly, the creator of the laurel/yanny sound edited the recording in the frequency domain to cause the aural ambiguity deliberately, whereas this is a natural piece of speech with some distortion in the high frequencies due to the recording medium.
Thirdly, whereas the laurel/yanny case was mysterious and surprising because on the face of it the two interpretations seemed completely different, in this case it’s not hard to see the similarity between /ðætsaʊndzlaɪkən/ and /ðætsəfʌkən/. If the diphthonging of the aʊ and aɪ are clipped, and the nd are missed, and the z becomes an f because of the aforementioned high frequency loss, then most of the work is done.
For mine, it sounds very much like what it is ("that sounds like an") but if I force my brain it will comply in hearing it as “that’s a fuckin’”. Funnily enough, it works better for me if I pretend Grover drops briefly into an Australian accent (which is my own accent): the American ʌ is somewhat central/schwa-ish, typically, whereas the Australian ʌ is a more open, /a/-like sound.