t-shirts don't get HP bonuses and damage reduction appears with a -2 penalty. (except for cow t-shirt!)
prerequisite stat for high-level t-shirts will usually be CONVINCE or LISTEN, ie, can you pull off the message it bears? do you *get* the band it namedrops?

Name QU AV REQS BONUSES TRAITS
old white t-shirt with two gaping claw marks 0 0 - - -
distressingly-stretched gray t-shirt 0 0 - - -
t-shirt with band logo your friends will mistake for far-right shit 0 0 - - -
tight t-shirt for meatheads 0 0 - - -
plain black t-shirt spraypainted to say JUNK ART AMATEUR 0 0 - - -
faded t-shirt featuring pornographic cartoon characters 0 0 - - naughty
t-shirt with the logo of a defunct rollercoaster 0 1 - Skill Access +1 -
baffling red t-shirt with "NOT REALLY" written on it 0 1 - Hack Pool Maxes +1 -
The Servants of Practical Purpose band t-shirt 0 4 Convince 2 Baelie Lore +1, Bonus Damage +1 -
PLACEHOLDERS band t-shirt 0 4 Listen 2 Hack Power +1 -
genuine The Awfs tour shirt from 1978 0 6 Convince 2, Listen 2 Max SP +1, Max MP +1 -
Spearmint Tower t-shirt for tourists 1 0 - Skill Access +1 -
dark gray Phasti t-shirt with ludicrous gladiator design 1 0 - Bonus Damage +1 -
tie-dye t-shirt 1 1 - Amp Pool +2 -
t-shirt proclaiming that you "no longer live in the fucking eighties" 1 2 - Luck +1 -
green t-shirt with a big cartoon cow 2 1 - Damage Reduction +1 -
long-sleeved "Ghosts a-Callin'" t-shirt 2 4 Listen 2 Bonus Damage +2, Hack Pool Maxes +2 -