How to make a toast in Sims 4

[ksskinner]

I cannot find a way for an adult to make a toast at a party. I would appreciate any help

[stitching_JA]

Your sim and another sim both have to have a drink in their hands for the option to be available, and the active sim needs to be at least young adult.  If one sets their drink down on a table or the bar between drinks, you can't do it, so you have to be observant and quick.  Have two or more sims chat, then make drinks for everyone.  I use two of my playable sims for this, and have them take their drinks to an open area away from the bar.  I find that makes it easier as they hold their drinks for longer.  The option to make a toast then shows up in the interaction pie menu when I click on the second sim. 

I'm not sure if there are also relationship requirements for the option; the sims I've had do it were all friends already.

[Playalot]

I think it's a wee bit glitchy. Sometimes it easy to do... other times it seems to take a bit of manipulation.
Basically once your controlled sim has a glass in their hand you can then click another sim and choose the 'make a toast option. Often the other sim doesn't even need to have a drink in their hand.
If that doesn't work (and sometimes it doesn't) you have to manipulate it again so there are two sims both with drinks, then click on the other sim with a drink.... make a toast!
If all else fails... wait until both sims have had a least one sip.... then click for the 'make a toast' option. As stitching_JA says, you have to be pretty quick to make this happen at times.

[oshizu]

Your sim and another sim both have to have a drink in their hands for the option to be available, and the active sim needs to be at least young adult.  If one sets their drink down on a table or the bar between drinks, you can't do it, so you have to be observant and quick.  Have two or more sims chat, then make drinks for everyone.  I use two of my playable sims for this, and have them take their drinks to an open area away from the bar.  I find that makes it easier as they hold their drinks for longer.  The option to make a toast then shows up in the interaction pie menu when I click on the second sim. 

I'm not sure if there are also relationship requirements for the option; the sims I've had do it were all friends already.

When I've done this party requirement, if the bartender isn't making drinks fast enough, I'll have at least two controllable sims just go to the fridge and grab an orange juice (Quick meal).
That gives me a greater chance of multiple sims drinking at the same time.  Apparently, the drinks involved in making a toast don't necessarily have to be alcoholic.
Also, you'll find "Make a toast" under the Friendly interactions.

[stitching_JA]

Thanks for the tip about orange juice, oshizu.  I just assumed the drink had to be made at the bar.  This should both save time and keep the glasses in the sims' hands for longer (I don't have a chair and table right beside the fridge).