What happens if you are caught with a fake ID?

I don't know why the college would find out, unless they were university police. You will probably get a fine and probation, unlikely you get jail time, but possibly community service or work alternative where you pick up trash along freeways. Get a public defender if you do not have money to hire a private attorney.

What is going to happen? Prosecution on the crime. You now have an arrest on your permanent record. If convicted, that too will be on your permanent record. That is the consequence of committing the crime. When charged with any crime, the proper questions are, can any evidence obtained in a search or statement be used against you, can you be convicted, and what can you do? While this isn't a 'capital case', it certainly carries potential jail time, so handle it right. No amount of free 'tips and hints' from here or elsewhere are going to effectively help in a legal defense. If you don't know how to represent yourself effectively against an experienced prosecutor intending to convict, then hire an attorney who does, who will try to get a dismissal, charge reduction, diversion, programs, or other decent outcome through motions, plea bargain, or take it to trial if appropriate.

A fake I.D. is covered under California Penal Code Section 529.5. (a) Every person who manufactures, sells, offers for sale, or transfers any document, not amounting to counterfeit, purporting to be a government-issued identification card or driver's license, which by virtue of the wording or appearance thereon could reasonably deceive an ordinary person into believing that it is issued by a government agency, and who knows that the document is not a government-issued document, is guilty of a misdemeanor, punishable by imprisonment in a county jail not exceeding one year, or by a fine not exceeding one thousand dollars ($1,000), or by both the fine and imprisonment. (c) Any person who possesses a document described in subdivision(a) and who knows that the document is not a government-issued document is guilty of a misdemeanor punishable by a fine of not less than one thousand dollars ($1,000) and not more than two thousand five hundred dollars ($2,500). The misdemeanor fine shall be imposed except in unusual cases where the interests of justice would be served. The court may allow an offender to work off the fine by doing community service. If community service work is not available, the misdemeanor shall be punishable by a fine of up to one thousand dollars ($1,000), based on the person's ability to pay. (d) If an offense specified in this section is committed by a person when he or she is under 21 years of age, but is 13 years of age or older, the court also may suspend the person's driving privilege for one year, pursuant to Section 13202.5 of the Vehicle Code. You are looking at a misdemeanor and if under 21 a loss of driving privilege for one year.