How can I tell my mom that I want to get all tattoos like boys my age.?

Respect your body. Many young people will later regret the mutilation that they do their bodies. Many conspicuous tatoos will make getting a job difficult later. Tattoos done without proper technique can lead to serious lifelong illness. Trust your moms wisdom to disapprove of your efforts to fit in. Wear your hat crooked, hair long, braids, whatever you need to rebel, but you may regret anything permanent.