First date with a good prospect tonight - would it be funny right after we sit down to say
‘Are you cool with me dialing my mom in on speaker?’ Then ‘I might also conference my therapist in after we order’
It made me giggle thinking about it while running yesterday..
So, your joke needs a re-write.
Good start with mentioning that you want to bring your mom in on the date, maybe make it sound just routine, you know, just in case she has any questions or suggestions for you or your date. Give the vibe that you don't want your mom to feel left out. Pull out phone to start dialing...then go for the laugh and say, "Just kidding, can you imagine.....
(She laughs, maybe smiles. Don't worry, she'll laugh later and maybe share it with her best friend.)
Then dead pan, say "But seriously, I do need to bring my therapist in, I just don't want things to get weird and I really trust what he says..."
Laugh again, put phone off and away and order some drinks.