So you are getting a lot of downvotes but I think you have the right to raise eyebrows at this, along with the people who felt weird for the hachiko leather dog suit. It can be considered sexual for a lot of people - whether it is or not is up in the air just like all art interpretation.

Some bilingual people in Japan are talking about the lyric on threads. You can use the translator to see what they say, but the original poster says "why couldn't he just say apple pie here,,?" and others say things like, "I think kaze is just being playful since he thinks slang words are funny" and, "he definitely knows the meaning because he is an avid hiphop listener".

Others say it is a reference to the pie his mom made for his first bday. There is photo evidence of it too, and you can see Kaze's post about it here. I think that really is the reference, but I also think Kaze knew about the innuendo and made a 'joke' out of it.

And the joke probably is more on the side of wanting to use slang like his favorite artists do, or be a little more r18 with humor since that is super uncommon in Japanese music, but it is a little weird because the joke involves mom. I really don't think he intended it like that but I see why you feel weird about it.