Chihuahuas are shockingly forbearing. Make 'em wear a toupee or a teddy bear outfit and they'll still just gaze at you like you're a trustworthy sod.
I've not yet been able to identify the chihuahua or the photographer of the topmost portrait of pup in teddy bear pyjamas. It has been reproduced all over the web without proper credit, though I hope yet to find out and provide that information here.
In the meantime, shown immediately above is a second chihuahua dressed up as a teddybear. That one was snapped by Ian Whalen.