You are should only claim the number of exemptions allowed for your personal tax situation. Form W-4 provides for a calculation to maximumize the exemptions allowed.
While you can claim as many exemptions as you want, it is in your best interest to claim the proper number based on your income and deductions. Should you have a large balance due next April due to under withholding, the IRS can require your employer to withhold at a level that it chooses. (I've seen it happen)
Hope this helps.
If you are satisfied with my work, kindly press the green "ACCEPT". It is the only way I am paid for assisting you. Positive feedback and bonuses are appreciated.