A trademark is an identifiable mark. From the USPTO's website: "A trademark is a brand name. A trademark or service mark includes any word, name, symbol, device, or any combination, used or intended to be used to identify and distinguish the goods/services of one seller or provider from those of others, and to indicate the source of the goods/services." Trademarks fall into two general categories: marks that identify goods or products (known as trademarks) and marks that identify services (known as service marks). An act - such as "Tebowing" - in and of itself does not fall into either, and therefore cannot be trademarked per se. The name of an act, however, or a logo/brand/etc. that is identifiable and ascertainable could be. For example, trademarking the "Tecktonik" word - used to describe a dance style. (See link)
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on as such, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal query without a comprehensive consultation and a review of all the facts and documents at issue. This answer does not create an attorney-client relationship. Vadim Alden is a licensed California attorney, and all answers relate to California law unless specified otherwise.
If you are simply asking whether you can do the act Tim Tebow does (kneeling in pray during football games) in your personal life, of course you can. If you are asking if you can run some kind of commercial enterprise and use the term "TEBOWING" with or without in image, that is a wholly different question. Tim Tebow has a number of trademark rights and if you are attempting to capitalize on his name and reputation, you'll likely risk getting sued. A trademark can be anything. It is usually a word or logo. But it can be a smell or even a movement. So long as it functions to identify a single source, it can qualify. Your question sounds to me like you are considering some kind of business and I would warn against it. You also my have right of publicity issues (using someone's name or likeness without their permission.) If you want to move forward with a business you definite need advise of experienced counsel.
Angie Small Booth, practicing trademark law for 25 years.
Comments provided on this website are not intended as legal advise and do not create and attorney client relationship.
Kapernicking (which is what you actually want to know about, right?) has been filed as a trademark by Colin Kapernick. http://bleacherreport.com/articles/1511519-colin-kaepernick-files-to-trademark-kaepernicking-before-super-bowl
Just doing it is not commercial use, so does not infringe the trademark, any more than if you hold up a 49ers banner tomorrow.
However, using a picture of it to peddle goods or services by free-riding on the reputation of Colin Kapernick ---well, that will apparently get you crossways with his trademark attorneys. If you do that you are implying that you are associated with the currently hottest QB in the NFL, when likely you are just ripping him off to try to get more for your items and divert customers of his to your cheap stuff. That should and likely will get you in trouble, perhaps just your goods get confiscated or perhaps you get cuffed and charged with a state or Federal crime.
So the question for you is "Feel'n Lucky Today?"
FYI, the right way to do this is to get permission and pay whatever the trademark owner asks. Good luck getting that in a timely fashion! Your odds are not about zero, they ARE ZERO.
Now if you want to Kapernick your stuff after the big game, then your odds increase to about 1 in a hundred million and you need a lawyer to even have that much chance. I will be waiting with baited breath [or maybe with just lawyer breath] for that call! LOL
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.