You may have heard this word from someone who enjoys anime. Sasageyo means to offer or to sacrifice. It is most well known from the popular Japanese series "Attack on Titan" or "AOT" It is from the season 2 theme song.
You can watch the full series on Hulu!
One example of this word being used in the show AOT is "Shinzou wo Sasageyo!" Which means to offer your hearts.