fridays are tie days -black watch regimental stripe
This is barely perceptible as a regimental stripe when worn which is half the point. Of all plaids, Black Watch is often deemed the most universally accessible, and appropriate for non-clan affilaites (though I have never seen of heard of anyone being bothered by what tartan you wore). Further reading. Anyhow, along those lines, for those that are sensitive about regimental stripes (ie not wearing them if you don't belong) I recommend the Black Watch Reg' Stripe.