it's mainly all about what frostweaver said, patience.
the trendy phrase changes where the feebas appear but since their
appearance also has to do with your trainer ID number
having the same phrase as someone else won't let them find feebas in the
exact same tiles as you.
Also, when you mix records with people, your tiles change
they catch feebas where you were able to and you catch it where they
were able to, so if your friends already got some, mix records and have them
show you the exact sqare where they caught theirs or, better yet just
trade with 'em and after you breed don't release them incase you want
to later on breed more.