1. sign up - Noun
2. sign up - Verb
engage by written agreement
join a club, an activity, etc. with the intention to join or participate
Source: WordNetsign-up
You know, I remember Career Day in high school. I remember plumbers and lawyers... I don't remember a booth where you could sign up to learn how to shoot chickens out of a cannon at the windshield of an airplane, 'cause there would have been a line at my school to do that! Jeff Foxworthy
I was planning to go into architecture. But when I arrived [to sign up for courses], architecture was filled up. Acting was right next to it. So I signed up for acting instead. Tom Selleck
I wanted to sign up and fight with you guys, but they told me I was too old. Bruce Willis
If they could offer up a way to go to the moon that wouldn't kill you, I'd sign up. Tom Hanks
I do a lot of marathons as training runs. If I'm somewhere and there's a marathon, I'll sign up and just go run it. Dean Karnazes
When my father passed away, he had his organs donated. In that painful moment, I was deeply comforted knowing that my father would be able to give others a second chance at life. That is why I encourage everyone to sign up to be a donor. John Perez