When I was small we lived in a flat above a greengrocer's. Whenever Doris Day came on the wireless singing, 'Que sera, sera' I always thought that she was singing, 'The fruit shop's (future's) not ours to see.
Not strictly a mondegreen, but every time I try to enjoy Justin Bieber's "Love Yourself", I can't help but substitute Ed Sheeran's original lyric on the last line..............
"Oh baby, you should go and love yourself"
Substitute Sheeran's original word on the penultimate word as you please ;o)