The unnecessary third wheel in a group of 3 people. Tin Dogs are usually insignificant people who spend all their time in the shadow of the others.
by Anomonon June 30, 2010

A highly useful but under-appreciated member of a group. Comes from a robotic dog ("K-9") from the "Doctor Who" TV series.
by peakeflix January 05, 2015

When your mate has a shit that just keeps smearing all around his ass crack like vegemite... give him the tin dog creek: you piss down his lower back and into his ass crack, allowing him to use the piss to wash his shit from around his ass crack
Ronny: Oi cuz, I can’t wipe this shit clear of my ass, gimme the tin dog creek aye?!
Cuz: no worries, spread that ol clacker of yours wide
Cuz: no worries, spread that ol clacker of yours wide
by Shadowscorpse June 12, 2018
