An outraged Park Slope teacher says he learned the hard way that it’s OK to wear Black Lives Matter t-shirts to work at his “woke” Brooklyn school — but not pro-cop or pro-Israel garb. Jeffrey Levy, an English as a Second Language teacher at MS 51 in the liberal Brooklyn enclave, told The Post that school Principal Neal Singh ordered him to stop wearing his “Proud Zionist” t-shirt in the building — even though other staffers have worn shirts touting BLM and women’s rights.