The longest day of the year is on Saturday. How will you spend it? This week: a play based on the works of Terry Pratchett, World Cup viewing parties in Grant Park, and festivals celebrating green living, Thai culture, and the joys of making music. And, as always, check Groupon for even more great things to do in Chicago. Cast of Monstrous Regiment. Photo courtesy of Lifeline Theatre. Monstrous Regiment Rogers Park | Through Sunday, July 20 The lively characters of Discworld comes to life in this Jeff-recommended stage adaptation set in Terry Pratchett’s beloved sci-fi universe. As Borogravia slogs through another war, a young woman enlists, defying military convention to find her missing brother. (Lifeline Theatre, 6912 N. Glenwood Ave.; $40, buy tickets here) World Cup Viewing Parties The Loop | Monday, June 16; Sunday, June 22; and Thursday, June 26 As the US men’s national team battles its soccer rivals in Brazil, fans back home will be cheering loud enough to be heard in South America. Join supporters in Grant Park for public viewing parties of matches against Ghana, Portugal, and Germany. Monday’s party includes a special appearance by hip-hop star Lupe Fiasco. (Grant Park, 337 E. Randolph St.; free) Thai Festival The Loop | Wednesday–Friday, June 18–20 The sights, sounds, and smells of Thailand turn Federal Plaza into Bangkok during this annual cultural expo sponsored by the Royal Thai Consulate. Muay thai demonstrations, traditional dance, and plenty of spicy food anchor a packed three-day schedule. (Federal Plaza, corner of Adams St. and Dearborn St.; free) Make Music Chicago More than 50 locations throughout Chicago | Saturday, June 21 This weekend, Chicago joins 460 cities across the globe in celebrating the international Fête de la Musique. Featuring amateur and professional musicians alike and encouraging audience participation, the free concerts fill diverse venues including coffee shops, churches, and outdoor spaces with song. (free) Guided by Voices, above, will perform at Green Music Fest on Saturday, June 21. Photo courtesy of the artist. Green Music Fest Wicker Park | Saturday and Sunday, June 21–22 Environmental awareness and hip music forge their annual alliance at this yearly Wicker Park festival. After browsing earth-conscious vendors, take in the sounds of alt-country crooner Bobby Bare Jr., lo-fi legends Guided by Voices, or the prog-pop of Moon Taxi. (Damen Ave. between North Ave. and Schiller Ave.; $5 suggested donation)