Untucked Dress Shirt With Jacket Girls Help A Guy With His Outfit For A Formal Party?

Girls help a guy with his outfit for a formal party? - untucked dress shirt with jacket

I have a company party the night that I have a jacket and dress pants are recommended. My plan is to use black striped dress very, very weak in him, do not think a tie is not required. I am also in my 20 years and I am looking for a younger look.

What do you wear a T-shirt under the jacket? Color? Style? hidden or untucked? All recommendations would be great thanly you!