Im afraid to lie to my mom, but if i tell her the truth she wont let me go?

Theres a party tonight and instead of having a DD me and my friend were going to sleep over. Everytime i hang out with that group they always say sleep over that way we all can drink. Im afraid to tell my mom that i would sleep over cuz shes not a fan of the people im haning out with, which is rediculus esp cuz the main reason is cuz the guy (i like but dare not tell my mom) is puerto rican and im white. My friend came up with the idea of me telling my mom id sleep over her house after the party instead of the guys house. Idk what to tell her because i dont want to lie to her, because if i lose her trust id be screwed. What should i do or say to make her okay with me staying over a guys house.. (everyone stays over that is at the party)