I can think of two other climactic tattoos in the SGR-verse:

-The creepy Black Metal Society tattoo from the pre-Boom Giant Days #3 (I think this was a dropped plot line)

-The photo-realistic tattoo Shauna’s step-dad got at the end of one of the Bad Machinery stories. That was a rare punchline (in anything) that made me actually LOL.

I think there’s a SGR flashback of Amy getting her ink as well, but I recall that happened off-panel (and possibly in Portland, Oregon?), and we already knew about her tattoos, so it wasn’t a climactic moment.

Needless to say, I’m looking forward to the reveal of Lottie’s mystery ink!