What is an OXYMORON?
Its when you say two words thinking they go together but they have totally opposite meanings.

From www.oxymoronlist.com
my favorite is number 1.

20. Government Organization
19. Alone Together
18. Personal Computer
17. Silent Scream
16. Living Dead
15. Same Difference
14. Taped Live
13. Plastic Glasses
12. Tight Slacks
11. Peace Force
10. Pretty Ugly
9. Head Butt
8. Working Vacation
7. Tax Return
6. Virtual Reality
5. Dodge Ram
4. Work Party
3. Jumbo Shrimp
2. Healthy Tan
1. Microsoft Works