| Razorblade Tuesday is raver slang for the Tuesday that follows Saturday night ecstasy use. If you've done much e, the derivation of the term should be obvious. This effect is due to low serotonin levels that are an after effect of the MDMA high. Feelings can can range from mild tiredness all the way to deep, black depression. This "hangover" tends to get a little worse and last a little longer each time the user takes ecstasy. Despite the name it can last anywhere from one to five days, but usually starts early Monday and is over by Wednesday.
Other slang terms for this feeling or period of time include Suicide Tuesday, Blue Monday, and plain ol' Hangover. Needless to say, it is in no way a pleasurable experience.
Don't confuse Razorblade Tuesday with Cracked-out Sunday, which is a different (but related) thing. Cracked-out Sunday is the day right after the ecstasy experience which usually feels sort of floaty and disconnected, along with some short term memory deficit. Instead of being caused by an ultra-low serotonin level, these happen when the level is ramping down, but hasn't yet reached rock bottom.
Clueful noders will notice that this was submitted on a Tuesday ;-) | 
