Wee as a weapon

[Trinaluce]

So we've been potty training for nearly a month now, getting on pretty well with only the odd accident (usually at nursery now). The trouble we're having is that she's peeing when she's told off! I don't know what to do about it - if we shout at her she just pees straight away (or if we say no she can't have something), if we go for the silent treatment and naughty step her she just pees all over the stair :(

(The reason for the telling off is a whole other issue: she's a pincher...)