Shh. It’s all in your head. LEARN Brainwave NYC What: Large-scale (six museums) long-term (six months) festival with mind as matter. Why: See a Jim Henson/Frank Oz collaboration; a Dutchman who uses tantric practices to raise his body temperature while immersed in an outdoor ice bath; a discussion on your potential superhuman qualities. When: Thru June. Check schedule for events listings. Where: Various cultural institutions. More info online at brainwavenyc.org. BUY Daryl K Sample Sale What: Summer, fall, and resort stock from ’07. Silk tuxedo tunics, were $520, now $150; pod coats, were $750, now $175; silk tops, were $360, now $80. Why: Oh, K? When: Sat. & Sun., 9:30 a.m.-7 p.m. Where: 21 Bond St., at Lafayette St. (212-529-8790). Elizabeth Charles Warehouse Sale What: Fifty to 90 percent off all stock in honor of Australia Day. Why: You’ll be the cutest thing throwing shrimp on the barbie. When: Thurs.-Sat., noon-7:30 p.m; Sun., noon-6:30 p.m. Where: 639½ Hudson St., b/t Horatio & Gansevoort Sts. (212-243-3201). EAT Crosby Connection What: The closet-size sandwich shop is closing — leaving the scent of Fatboys and meatball sammies in its wake (at least until they open their new location). Why: Salute lunchtime heroes. When: You’ve got until Feb. 1. Mon.-Fri., 11 a.m.-4 p.m. Where: 172 Crosby St., at Bleecker St. (212-677-8444). DO Gentle Waves Treatment What: The service, to reduce redness and increase firmness, is complimentary (reg. $125) when you book a derm consult. Why: That’s the wave it goes. When: When you’re sagging. Where: 568 Broadway, at Prince St., ste. 303 (212-334-1155).