xkcd T-shirts

BEST SELLER! Now available in women's sizes as well as unisex.

Stand back! I'm going to try science.
Unisex t-shirts are printed on a somewhat lighter weight shirt than our usual heavyweight t-shirts. Ladies' t-shirts are printed on a heavyweight t-shirt.
T-shirt is Black.

Finally, an explanation for non-techies of how to troubleshoot a program, in flow-chart form.
This design is printed on a somewhat lighter weight shirt than our usual heavyweight t-shirts.
T-shirt is Black. Available in Small only. $20.

Features a valentine heart as the argument for functions from algebra, trigonometry differential and integral calculus, and linear algebra, with the caption "My normal approach is useless here".
This design is printed on a somewhat lighter weight shirt than our usual heavyweight t-shirts.
T-shirt is Black. T-shirt is Black. Available in XL ($20) and 2XL ($22) only.

This cartoon discusses the relationship between correlation and causation.
This design is printed on a somewhat lighter weight shirt than our usual heavyweight t-shirts.
T-shirt is Navy Blue.

Price: $20 ($22 for 2XL).