¿Qué significa la expresión: drinking from the firehose?

Ejemplos:

• "To be overwhelmed (with information, work, etc.); to do something intensely; to be inundated"
• "I'm still drinking from the firehose, learning all about working in this new world that I find myself in". 
• "I've been drinking from the firehose this semester, trying to pass all these chemistry courses".

Fuente: Urban Dictionary