Please hold on whilst the bus is in motion.

[Imralu]

Announcement on buses in Berlin.

Liebe Fahrgäste, zu Ihrer eigenen Sicherheit möchten wir Sie bitten, sich während der Fahrt festzuhalten.

Dear passengers, for your own safety, we would like to ask you to hold on whilst the bus is in motion.

Swahili
Abiria wapendwa, kwa ajili ya usalama wenu tunawaombeni mshikilie tukiendesha.
abiria wa-pend(a)-w(a) | kw-a ajili y-a usalama wenu | tu-na-wa-omb(a)-(e)ni m-shikili(a)-e tu-ki-end(a)-(l)e/ish(a)
passenger(CL9/10) CL2-love-PASS | CL17/15 sake(CL9/10) CL9-GEN safety(CL14) CL14-GEN.2P | 1P-PRES-2P/3P-request-2P 2P-hold.on-SBJV 1P-SITU-go-CAUS

I might gloss the German later when I have time, but someone else is more than welcome.

[Alessio]

This is a very interesting sentence, as it allows me to show the difference between formal and informal Italian.
I never heard this sentence on our public transports, so this is completely made up, but it certainly resembles what one expects to hear.

Italiano - Formal Italian used for broad communications
Si pregano i gentili passeggeri di afferrare saldamente un elemento dell'autobus ai fini di evitare cadute durante la marcia del mezzo. Grazie.
/si 'prεgano i dʒen'tili passed'dʒεri di affer'rare salda'mente un ele'mento del'l‿au̯tobus ai̯ 'fini di evi'tare ka'dute du'rante la 'martʃa del 'mεddzo 'grattsje/
si preg-ano i gentil-i passegger-i di afferr-are salda-mente un elemento de-llo autobus a-i fin-i di evit-are cadut-e durante la marcia de-l mezzo grazie
IMPERS pray-3PL DEF.MP gentle-MP passenger-PL of grab-INF firm-ADV INDEF.M element of-DEF.MS bus to-MP purpose-PL of avoid-INF fall-PL during DEF.FS journey of-DEF.MS vehicle thanks

Note that this form uses an impersonal particle, specifically a medio-passive reflexive, as if they didn't want to say who is requiring this.

How I would say this to a friend:
Tien(i)ti stretto! (dropping the <i> is common around here, but I think it's non-standard everywhere else in Italy)
/'tjεniti 'stretto/
tien-i-ti strett-o
hold-IMPER-REFL.2SG firm-MS

How I would say this to someone I don't know:
Signore/a, Le consiglio di tenersi stretto/a.
/siɲ'ɲore le kon'siʎʎo di te'nersi 'stretto/
signore/a le consigli-o di tener-si strett-o/a
sir/madam 3SG.DAT.FORMAL advise-1SG to hold-REFL.3SG firm-MS/FS

[Iyionaku]

Yélian

Formal Yélian is a lot less well-developed than colloquial Yélian.

Kégaloraniatsan, ren sanet ivàcatest pi ropuatrein fum yan rucanurunten yanim tayim. Nailet sanim iaruvan tyamarganut.
[ˈkeːxɐlɔ̈ˌɾanɪ̯ɐt͡sɐn, ɾən ˈsaːnət ɨˈvɐːkɐtəs‿pɨ ɾɔ̈pʉˈatɾɛɪ̯n ɸʉm ʃɐn ˌɾʉkɐnʉˈɾuntən ˈʃaːnɨm ˈtaːɕɨm. ˈnaɪ̯lət ˈsaːnɨm ɪ̯ɐˈɾuːʋɐn t͡ʃɐmɐɾˈgaːnɨt]
passenger-highly_withheld-PL, 1PLEX 2PL.OBL VOL-ask-1PLEX that FUT-hold_on-2PL while 1PLIN together-perform-1PLIN 1PLIN.OBL drive | that_way 2PL.POSS safety POT-guarantee-INV.3SG.INAN
Literally: Revered passengers, we want to ask you to hold on whilst we perform our drive together. That way, your safety can be guaranteed.

[Parlox]

Lozkazmat

Mlagz ok bözganag, gel jeurbouz jëzcqag, amp euz socqam jeurp er’ keuzqon hounas, eup bözganagmecq ol r’oz h’ajazor’.
Good many passenger, for 2ND-with safety, 1ST.PLUR MOM appreciate 2ND.PLUR PROG hold tight, that bus GNOM in motion.
Dear passengers, for your own safety, we would like to ask you to hold on whilst the bus is in motion. (Lit, Good passengers, for your safety, we would appreciate you holding tight, the bus is in motion.)

[Reyzadren]

griuskant (without the conscript)

ki cuike. plidar vozh duzzir hin pauj.
/ki 'tʃuikə. 'plidar vɔʒ 'duzzir hin 'paudʒ/
to ride-N. hold-V-IMP during bus.go for safe.

[Iyionaku]

Lozkazmat

Mlagz ok bözganag, gel jeurbouz jëzcqag, amp euz socqam jeurp er’ keuzqon hounas, eup bözganagmecq ol r’oz h’ajazor’.
Good many passenger, for 2ND-with safety, 1ST.PLUR MOM appreciate 2ND.PLUR PROG hold tight, that bus GNOM in motion.
Dear passengers, for your own safety, we would like to ask you to hold on whilst the bus is in motion. (Lit, Good passengers, for your safety, we would appreciate you holding tight, the bus is in motion.)

Is this a natlang or a conlang? Your signature says you learn it, but I cannot tell if this is rhetorical. I have never heard of this language before.

[Parlox]

Lozkazmat

Mlagz ok bözganag, gel jeurbouz jëzcqag, amp euz socqam jeurp er’ keuzqon hounas, eup bözganagmecq ol r’oz h’ajazor’.
Good many passenger, for 2ND-with safety, 1ST.PLUR MOM appreciate 2ND.PLUR PROG hold tight, that bus GNOM in motion.
Dear passengers, for your own safety, we would like to ask you to hold on whilst the bus is in motion. (Lit, Good passengers, for your safety, we would appreciate you holding tight, the bus is in motion.)

Is this a natlang or a conlang? Your signature says you learn it, but I cannot tell if this is rhetorical. I have never heard of this language before.

Lozkazmat is my main conlang, and it is not rhetorical.