By Whoism, I assume you mean “an ism’ that is used in Doctor Who. And by “ism” I assume you mean something that is said/done so much you can only associate it with Doctor Who.
The term “Stupid face” as a term of endearment. I call my little sister that almost all the time, but she knows I mean it in the best way possible. I don’t know if that really counts though, since we do it for fun.
"I wear a ___ now, ___ are cool"/"___ are cool" and "Bananas are good" are 2 that I use pretty frequently. I am also known to use "Allons-y" a lot before heading off soemwhere. I love that one! Sometimes I use "Spoilers" but not as much as my friend does.
Once or twice when somebody asked for the time I said “Wibbly-wobbly, timey-wimey…stuff.” while I took my cell out of my pocket. It destroyed that awkward silence there was while the other person patiently waited…and confused the hell out of them.
Also, I stare at statues & count shadows…a lot. Is that a Whoism, or is that just an irrational fear? xD
But I often make many other connections to Doctor Who in a conversation that nobody else would. I also throw DW quotes that work in my situation into a conversation and wait for others to notice. It’s fun ^_^