In my talk, I will speak about the chromatic numbers of random subgraphs of some graphs, whose vertices are $(0,1)$-vectors in ${\mathbb R}^n$ with exactly $r$ non-zero coordinates and whose edges are drawn between some two vertices, if and only if the inner product of the corresponding vectors equals $s$ (so that the distance between them is $\sqrt{2(r-s)}$). Note that for $s = 0$, we get random subgraphs of Kneser's graphs.