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but can you get a vest, or i guess i could make one, but a vest that has tails?
Yes, it's possible to put tails (like a tail suit) on a vest, but I strongly suspect you'll have to make it yourself, or get it custom made.
If you want to make it yourself, you'll need to make a mockup (a test garment in cheaper fabric) first, as you'll probably need to play with the hang/shape of the tail section to get the look you want. In terms of making the pattern it's fairly easy, take the back pattern piece and extend the centre back seamline straight down - you'll probably want it down to the back of your knees. Then from the side seamline, drawn a line straight down for a bit and then curve it towards the end of the first line in a shape you think aesthetically pleasing.
Now depending on how curved your back/buttocks area is (looking on side view, most people poke out a bit at the shoulderblades, go in at the waistline, and go out again over the curve of your buttocks) you may find you need to either curve the CB seam a bit, or take a horizontal dart (wider at the CB, to almost nothing towards to side seam) at the waistline - or both. You can either leave the dart at the waistline, or extend the line all way across to the sideseam and make it a waistline seam (remember to add seam allowance to both edges).
For the purpose you're looking at, it's a vest if it doesn't have sleeves (so your shirt sleeves show) or a jacket if the sleeves are the same fabric as the body. And remember too, the way the tails will behave (hang) will depend an awful lot on what fabric you use, if you line it, or even interline it.
Do keep us updated on your progess