If you use your credit card long enough, sooner or later that sensitive magnetic strip will get worn down and no longer swipe properly. While you're waiting for your replacement card, here's a quick fix: Tape over the magnetic strip.
Photo remixed from an original by Mettus / Shutterstock
Wired explains why this works:
A credit card is like a cassette tape. And just as your old copy of Van Halen II got fuzzy after hundreds of repeat performances, a credit card slowly gets garbled from overswiping. The reason: Both the tape and the magnetic stripe on the card are made up of millions of iron-oxide particles that convey information by generating electrical pulses in the reader. With wear, these particles get smeared, creating background noise. Luckily, this noise has very low magnetism, and it can be dampened by increasing the space between the magnetic stripe and the head that reads it. So simply cover the stripe with Scotch tape. If only reviving David Lee Roth's career were that easy.
For more scientific ways to improve your life, see the whole Wired article below.