“Bip Bop” is the second track from Wings’ debut album, “Wild Life“, released in 1971. It was the first song of the album to be recorded, but one of the last ones to be mixed.
Paul has consistently expressed his dislike for this song since releasing it, saying, for example, in 1986:

[S]ometimes a critic will say, “That’s really lousy” – and I’ll tend to agree with him: “He’s right, it’s not very good, that one.” I know there are quite a few tracks on my albums that I just don’t like now. Like “Bip Bop,” off Wild Life – oh, God, I can’t listen to it; it just goes nowhere.

That being said, he has more recently expressed that he doesn’t hate it as much as he once did, saying in 1997:

I remember saying to Trevor Horn that I really hated the songs from that period. And he asked which ones. “There’s a terrible little thing on Wild Life called Bip Bop”, I said, “It’s just nothing”. And he said “You’re kidding, man, that’s one of my favourites!”. My son’s been playing it recently and I think it’s a cracking little track. I’d gone with the current opinion at the time, that it wasn’t much good.