BLAME IT ON RIO: Titilate your tastebuds at the "Cachaca 101" cocktail class at River North's Zocalo tonight. You'll learn how to craft two cocktails -- a Cabana caipirinha and a guava margarita -- using seasonal fruits and Cabana Cachaca, a Brazilian spirit made from sugarcane. Zocalo will set up a traditional taquiza station with grilled and braised meats, homemade salsas and handmade tortillas, and guests will be entered to win a variety of raffle prizes. 6-9PM, $20.
ECO-NERDS: Attend one of the popular Nerds at Heart dating parties at Holiday Club in Uptown tonight, this time with a "green" bent. The second annual Earth Day Bash will feature the usual accoutrements -- board games, trivia contests and the like -- along with fair-trade chocolate samples from Greenheart Shop and Eco-tinis made with Rain Organic Vodka. The parties are open to straight and gay "nerds." 7-10PM, $20-$25.
TALKING HEADS: The Chicago Theatre's "Speaker Series: The Minds That Move the World" continues tonight with Chris Matthews interviewing Tucker Carlson, Arianna Huffington and Paul Begala about "Free Speech and the Power of the Press" live on the theater stage. 7:30PM, $38-$150.