Those are two words I almost universally want to avoid, except when one of them is perfect in a sentence within its context.
Normally, they’re both extra/trash words. Sentences are usually stronger without them. But in dialogue or monologue, sometimes just or because become necessary to render a character or tone or mood of a situation.
The word because can almost always be eliminated—when B follows A, because is implied: “A because B” is most always better stated as “A B.” The reader adds in the because.
And just: “Girls are just panty dropping freaks.” That sentence really needs the just—it suggests a limitation at a bound. I think (for me, in general) that justs who do not suggest this cropping at a boundary can be removed.