Uhh wow. Hmm. I guess your best course of action depends on WHY they’re mad? If they’re mad about the language, you can apologize and tell them you won’t use that language where they can see/hear it anymore. If they’re mad because the poem suggests you’ve had sex (GASP!!), you could always lie (?) and remind them that poetry is often fiction. If they’re mad because they think this poem is going to tarnish your reputation or something, you can show them Vice or some other online publication where people are able to get hired and write for money despite being (what some would consider) lewd, immodest, crass, etc.
To be honest, if this was my parents, I’d probably just laugh and tell them to get the fuck over it because it’s 2014, but I realize that’s not necessarily the safest or smartest course of action depending on how reliant you are on your parents.