Red Tick

There's some thing a little perplexing about this sign from a hospital toilet area.  It's one of those issues hidden in plain sight.  It's because the tick and it's colour are at odds with each other.  We're more used to seeing green ticks and red crosses, so the red tick is what throws us, but without at first realising why.  Sometimes that juxtaposition can be an intentional thing to encourage or force that thinking and to hold the attention that bit longer to make a connection.