What's your worst experience tabletop gaming?

Something like 9-15 tanks vs 1 kind of shitty tank, 1 mech, 2 transports and ~20 infantry. Also Space Marines aren't as OP on tabletop as they are in the lore, like their standard boltgun can't do much against a vehicle. The Predator and Dreadnought would've been the only things that could do more than scratch the paint on the tanks, unless the tactical squads had a meltagun each (2 marines would've been able to poke holes in the tanks) and a heavy weapon like a missile launcher (2 more guys who can poke holes in tanks, but the whole squad might have to sit still for the missiles to be fired, depending on the edition).

Edit: and Dreadnoughts are on the smol end of mechs in 40k. Leftmost in this image, although up to Telemon are (non-basic-b-word) Dreadnoughts too. Armiger and the mechs to the right are Knights, which are smol titans.

Including titans (extremely not basic-b-word 40k):

Just newbie-stomping, which is generally frowned up on in every hobby.

But specifically in this case some of his vehicles have an Armor Value of 13 like the tanks, but I have no dedicated anti-tank so the highest strength weapon I had was Strength 8 and I had maybe 4 things that could reach that, 3 of which were melee, so I basically would need to roll a 5 or 6 to "wound" the Armor Value 13 Tank aka mathematically unlikely when he has multiple weapons and tanks to target my units that had the Strength 8 weapon because I have a beginner's list and then he would newbie-stomp