Answer #50 : A hard rebus puzzle : Puzzlogram.

Q: What does the following puzzlogram mean?

O_ER_T_O_

A : Painless Operation!

Explanation:

1. As you thought, it's a single word with some missing letters. First find the word.
2. The word is "OPERATION".
3. Now have a look at the letters you just added to complete the word.
4. The letters are P,A,I,N
5. So it's OPERATION without PAIN.
6. That is PAINless OPERATION.