It has multiple meanings depending on the conversation.

It is another way of saying "OMG, or "Are you for real?", or more commonly used, "Yeah,... right"
Mattie enters Debbies sanctuary and Debbie is alarmed and says loudly, "Your'e back again?! Say swear!"
by SAYSWEARFOOL April 11, 2010
Get the say swear mug.
exclamation said in response to being told something super awesome you are hesitant to believe.
theodore: ...and then she just straight up grabbed my d*ck in the middle of the lecture!
chadwick: say swear to god!
theodore: *holds hands up to show that no fingers are crossed* swear to god! she just grabbed my sh*t!
by geegz April 8, 2009
Get the say swear to god! mug.
something you say to somebody when you don't really give a shit about their story. this is a phrase usually used when somebody else won't shut the fuck up about something you don't give a fuck about. you usually let them talk for a little while but when they get to the point of being annoying, that's when you tell them, "Say I swear to God." In short, it's just another way to let somebody else know you don't care. When you tell them to say "I swear to God," they usually get the message right away after saying "I swear to God," and shortly afterwards realizing that it means you don't care.
Melissa: Cancun was so awesome! We were at the bar every night! We met totally hot guys! One night we all danced on the bar after we did like, 20 jelly shots apiece! And then Jill made out with some guy who was like, 35 years old! We were all dying laughing! It was so funny!

Me: No way! Say I swear to God! (in a cocky ass, sarcastic manner)

Melissa: I swear to God! (realizing you don't care)
by TwanDiggity August 10, 2005
Get the say i swear to god mug.
1. The funniest group of friends to ever grace the planet.

2. Asking someone if they're being serious or are lying.
Jacob: Say swear you haven't seen the new podcast episode.
Kelly: Hell nah I'm about to watch it now.
by Jhinxx May 12, 2023
Get the Say Swear mug.