Originally Posted by RadioKid
I think "しょくじをします:SHOKUJI WO SHI-MASU;I will have meal" is the right form. and " しょくじします:SHOKUJI SHI-MARU;I will have meal" is just having "を：WO" omitted and sounds rude.
"しょくじします:SHOKUJI SHI-MASU" is also recognized as "noun+SHIMASU" but when "WO" could be added, it sounds like rough or rude talking.
Thank you RadioKid.
So without "wo" does it really sound rude or just a bit informal?