1.Dont know when to shut the fuck up.
2.Talks before thinking about what they are saying or why they are saying it without consideration for consequences.
3. Big mouth, loud mouth, Macho mouth.
4. Diarrhea of the mouth.
5. Talk the talk but too scared to walk the walk.
Someone who says they are great at playing pool until they get on the pool table and then can't make a ball in the hole; and have nothing but excuses afterward.