Hilarious effect for the adult audiences!
Ask for a male volunteer from your audience.
Two handkerchiefs are tied together, the knot is tucked (discreetly & tastefully) into the front of the volunteer's shirt, and you and your volunteer each hold the tip of a handkerchief.
You tell your audience, on the count of three, you & your volunteer are going to pull on the handkerchiefs, making them pass right through the volunteer's body without harming him a bit.
But when you each pull on a handkerchief, a BRASSIERE appears, tied between the handkerchiefs! It's a silly surprise that will make everyone laugh, including your volunteer!
This trick is also funny if you use it on yourself