V-Neck shirts, especially if they dip pretty low. Also a lot of 'emo'-type stuff, because they're basically girls clothes marketed to boys.

Really any clothes that might make you look 'gay', because they'll essentially be effeminate guy clothes. However, going for that kind of look could just give you different problems.. I suppose you could at least wear more 'girly' colours, like pinks, purples, and pastels. Maybe wear more accessories? Jewelry can often be unisex, like earrings for example. Eyeliner if you can pull it off, especially if you go for some emo, goth, or rocker styles. This might be a stretch, but a 'travel bag' like this could act as a purse:
http://www.amazon.com/gp/product/B007XAI4M6/ref=s9_hps_bw_g198_ir15?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-7&pf_rd_r=0K9WFN5DZD17SYHX4XKD&pf_rd_t=101&pf_rd_p=1615661222&pf_rd_i=2602603011 However, be warned, as benign as some of this stuff might seem, others might think differently and could make their own assumptions. I did most of this stuff at one point for similar reasons (living with my parents while they didn't know). Eventually, I think my mom got suspicious and went through my things one day while I was out. Found out from my sister that my mom found a purse or makeup bag in my closet, but she never mentioned it. Or this other time I bought a tight purple hoodie and my mom said I looked 'gay' wearing it.

Finally I got daring enough, I went out with my parents to a restaurant wearing a red v-neck t-shirt, I had long hair, wore my earrings, and carried my bag/purse. And I got a 'ma'am' from the waiter! I was both flattered and mortified.

So just be careful with all of this. Things might be fine individually, but don't go overboard if you don't want to get caught..