Bob and Rob are identical twins. They look alike in every measurable way, but Bob lies on Monday, Tuesday, and Wednesday, whereas Rob lies on Thursday, Friday, and Saturday. Both of them tell the truth on Sunday.
You come upon Bob and Rob one day and introduce yourself to them.
One twin (twin A) introduces himself as Rob and warns that he will lie tomorrow.
The other one (twin B) looks up in surprise and tells you that he is Rob. He also says that he lied yesterday and that he will also lie tomorrow.
Who is Bob, who is Rob, and what day of the week is it?