There are three ways of overcoming a blockage the two most common: cashing the blocking honors (=unblocking) and then communicating through another suit (the usual manner) or sacrificing an honor by overtaking it with another higher honor situated in the opposite hand. The third method occurs less frequently than the first two, but it is also much more spectacular. It consists of discarding one or more blocking honors!
Here is a simple example:
7 Diamonds is the best contract (thirteen tricks by way of a Spade ruff), but you play in 6 No-Trump and get a Spade lead, the only one that causes you a problem. To overcome the blockage in Diamonds you must win the Spade lead in hand and then immediately cash your two remaining Spade honors, discarding the Ace and King of Diamonds from dummy! You can then start cashing your Diamonds, hoping that the suit breaks 3-2 (hooray, it does!) and then finish with the Ace of Clubs and Ace-King of Hearts.