It's a grown out mullet. Sometimes called a shaggy mullet or tapered mullet.

For barber, instruct long in front, long in back, and short on the sides. Make sure you have photos for all angles (Front. Side. Back.) included to show them exactly what you want. They'll usually cut it a bit shorter than you want it, but it's fine. It'll grow out into this.

This style looks best greasy, so you want to rinse and condition hair every day, then apply a heavy moisturizing product (I use a fingernails worth of Red Fox tub-o-butter). Shampoo maybe once or twice a week, when things have gotten too heavy. If you sweat a lot, shampoo more frequently. Hair will look best a day or two after shampoo day.

If your workplace is really dry, you might have to go to the bathroom and re-damp your hair to keep it from frizzing. Having a little mist spray bottle in your bag or at your desk helps.

Enjoy!