Many landlords require parent cosigners to sign guarantor forms. Beware that your cosigner or guarantor may be accepting liability not only for you, but also for your roommates.
You may want to add language to the cosigner or guarantor agreement stating:
Guarantor's liability is limited to the share of rent and damages attributable to Guarantor's son or daughter. Although tenants may be jointly and severally liable, Guarantor is not responsible for the liabilities of tenants who are not Guarantor's son or daughter.
Guarantor liability is tricky. Your potential guarantor should seek legal advice to determine whether the above language would adequately limit the guarantor's liability.