It's a Spanish-language variation of "dope" in its meaning of "cool" , "good", "great", etc. with the "loco" part of the expression only there because it rhymes with "dopo", wrongfully represented as "dopeo" in a separate entry (instead of "dope-o")
from Italian, lit. "first the mom, then the daughter"; used to designate a mom/daughter tag team sitch; where a cougaror soup chicken older woman uses her daughter as a wingman in a pathetic attempt to rejuvenate her doomed sex life. Often leads to either a threesome or a swapping situation.
"Eh, Robby - check out the two brunettesdrinking appletinis over there -- it's prima la mamma e dopo la figlia time, bro!!"